brief for beap electrical investigators / engineers · web viewall limits for a continuous-rated...

Brief for BEAP electrical investigators / engineers

The aim of BEAP is to baseline the capacity, condition and compliance (in that respective order) of Defence base infrastructure.

Scope boundaries –

Electrically, this means the capacity, condition and compliance of: incoming power supplies, intake substations, HV ring mains distribution, HV substations including HV substation building and switchgear, LV switchgear immediately downstream of substation transformers (only), localised generation (LEGS), central emergency power generation (CEPS), and central power

stations (CPS).

It generally does NOT include: compliance to Australian Standards for infrastructure owned by a Distributed Network

Service Provider (DNSP) e.g. compliance to Australian Standards of incoming supplies owned by an electricity network provider N.B. compliance to MIEE is still assessed!

A detailed examination of auxiliary LV switchboards at intake substations (the HV switchboard is the main concern)

Removing covers from HV switchgear (other than opening LV control panel doors) Excavations around buried cables Maintenance activities e.g. Oil sampling from power transformers, infrared heat checks on

LV switchboards Assessment of LV reticulation i.e. LV cable routes etc. (except if the incoming supply to the

base is at low voltage) Assessment of LV switchboards other than the main distribution board immediately

downstream of a substation transformer the non-electrical aspects of a LEGS/CEPS/CPS, unless there are obvious non-compliances.

For example, the escape route from a CEPS substation would be risk assessed for its general suitability, and the fire protection of the generator halls would be assessed from the electrical perspective of maintaining generation from an adjacent hall during a fire in one hall, because fire separation is a requirement of MIEE. However, for example, the mechanical suitability of a fuel line position would generally not be subject to assessment. If there are obvious non-electrical non-compliances, note that further investigation needs to take place, but try as much as possible to stick to the budget and avoid doing non-electrical inspections as part of BEAP.

Regardless of the above scope boundaries, if during investigations, the base personnel happen to bring to attention a particular problem that is outside the scope of BEAP, it is best to note the reported problem then include it in the BEAP issues register, even if it is only included as “Assess aspect …abc… of the CEPS for mechanical/structural suitability because problem …xyz… was noted by base personnel.”

The most important scope items are the incoming supplies, the intake substations, the ring mains and generation. These are items necessary to support all base operations. Individual substations and individual LV switchboards, while significant within a locale or to a specific facility, are relatively insignificant to overall base operations and therefore relatively minor to BEAP.

Base Engineering Assessment Program Checklist Templatedocument.doc of 31

BEAP is a risk assessment. It is not a compliance audit. Therefore, only the essential requirements for maintaining a reliable electricity supply and maintaining the safety of personnel and electricians is assessed. Future power demands are not considered. The essential aspect of BEAP is to assess the capacity, condition and compliance of the HV electrical network and report on its ability to maintain, safely and reliably, the existing level of base operations.

Reporting guidelines–

Justification: So that the BEAP reports are reliable, Defence requires that all evidence be documented in a written form. If anecdotal evidence is all that is available, the anecdotal information needs to be confirmed by an email.

Condition vs. compliance: For the report analysis, endeavour to put blinkers on, and see condition issues separately to compliance issues. If they overlap, endeavour to analyse what the root cause of each particular problem is, evaluating whether it is a non-compliance that causes unacceptable condition or vice versa. Primarily report the issue in the section allocated for the root cause. Cross-reference the issue in the other section as necessary.

Analysis structure: If major issues are encountered with any particular infrastructure component, the easiest report structure to use seems to be first to explain:1. what exactly is installed, then 2. the observed flaws / evidence for poor condition / non-compliances, then 3. analyse the causes, and lastly4. clearly state the risk to Defence and recommend remedial actions. To approach it in any other order has not worked before.

Capacity Terms: Utilisation = how much capacity is used divided by how much capacity physically exists in

the component (e.g. 30A drawn from a transformer rated for 100A is 30% utilised) Spare capacity = opposite to utilisation = how much capacity is not used, compared to how

much physically exists (e.g. 30% utilisation is equivalent to 70% spare capacity)

Through the analysis section of each BEAP report, the capacity needs to be discussed in terms of utilisation rather than spare capacity. Only at the summary sentence in the ‘Assessment Outcomes’ section does spare capacity generally have its first mention.

Criteria: Refer to the start of the report template (Part 3 - Electrical, Tables 2 to 4) for the relevant assessment criteria. A copy is included in this document for reference.

Drawings –

BEAP is expected to produce a site single line diagram (SLD), a set of colour-coded SLDs and a set of colour-coded GIS maps. Remote sites do not require a site SLD unless there is HV at the site.

Site SLD - The following items need to be recorded on the BEAP single line diagram:

o Xxx

SLDs – One copy of each of:

o Site SLD (no colour), drawing number BEAP-<3-letter site abbreviation>-ELEC-001-<capital letter of revision> e.g. BEAP-OAK-ELEC-001-B


o Capacity, colour-coded, drawing number BEAP-<xxx>-ELEC-002-<x>

o Condition, colour-coded, drawing number BEAP-<xxx>-ELEC-003-<x>

o Compliance, colour-coded, drawing number BEAP-<xxx>-ELEC-004-<x>

Colour-coded GIS maps –

o Overview – The following items generally need to be depicted:

Incoming supply cables (these are only required if they are in GFIS or if owned by Defence, otherwise consider a note to say they are not shown)

ISS locations

CEPS locations

LEG locations

HV substation & switching station locations

HV cable routes, colour-coded for each individual ring mains

Main LV switchboard locations (only for remote sites without any HV)

Do NOT show: (unless the site has no HV distribution)

Main LV switchboards

LV cable routes

o Main site: Overview, Condition

o Remote sites: Overview, Capacity, Condition, Compliance


Capacity, condition and compliance criteria:

Table 2 Engineering Service Assessment parameters

Criteria Used for Infrastructure Sub-Service Assessments

Capacity Condition Compliance1,2

ExceededA percentage of service capacity has been used or exceeded as listed in Table .

UnserviceableNot capable of functioning as intended, obsolete equipment / components, unable to be maintained – requiring full replacement / upgrade.

Non-compliant (AS and MIEE)Design does not comply with applicable mandatory design guidelines, Australian Standards and additional Defence Policy requirements.

Marginal A band of service capacity has been used as listed in Table .Likely to be non-compliant with requirements for spare capacity.

PoorDeterioration is severe and is limiting the serviceability of the asset. Maintenance cost would be high.

Non-compliant (AS) and Compliant (MIEE)Design does not comply with applicable mandatory design guidelines and/or Australian Standards, but complies with additional Defence Policy requirements.

FairDeterioration is obvious and there is some serviceability loss.

Compliant (AS) and Non-compliant (MIEE)Design complies with applicable mandatory design guidelines and/or Australian Standards, but does not comply with additional Defence Policy requirements.

Within Limits A percentage of service capacity has been used as listed in Table .

GoodSigns of deterioration evident, serviceability would be impaired very slightly.

Compliant3

Design complies with applicable mandatory design guidelines, Australian Standards and/or Defence Policy requirements.

As newNo visible sign of deterioration, recently constructed / installed or recently rehabilitated back to new condition.

Notes:

1. Non-compliance to Defence Policy requirements is assessed as non-compliance only to those requirements which are additional to the minimum standard of the Australian Standards or other mandatory guidelines.

2. Additional Defence Policy requirements can include physical and/or capacity requirements.

3. Compliance to the standards and Defence policies is an overall assessment that there are no obvious and significant deviations from the principles, which are in the standard, and which are required for maintaining the safety of the installation.


Capacity is assessed according to various bands of sub-service capacity as detailed in Table 3.

Table 3 Capacity Assessment Criteria by Sub-Service

Sub-Service Assessment parameter Within Limits Marginal Exceeded

Incoming supplies

Max. site demand compared to authorised demand <80% 80%<x<100% ≥100%

HV switchboards Max. current compared to busbar rating <85% 85%<x<95% ≥95%

HV network cables

Steady-state load compared to cable protection setting or cable capacity <80% 80%<x<95% ≥95%

HV substations Max. current compared to transformer rating

Oil transformers<85%

Dry transformers<75%

Oil transformers85%<x<100%

Dry transformers75%<x<90%

Oil transformers≥100%

Dry transformers≥90%

LV switchboards Max. current compared to busbar rating <85% 85%<x<95% ≥95%

CEPS1

Alte

rnat

or

Peak load (kVA) of supported services compared to prime capacity

<90% 90%<x<110% ≥110%4

Average load (kVA) of supported services compared to prime capacity

<70% 70%<x<80% ≥80%5

Engi

ne

Peak load (kW) of supported services compared to prime capacity

<90% 90%<x<110% ≥110%4

Average load (kW) of supported services compared to prime capacity

<70% 70%<x<80% ≥80%5

CPS

2 Prim

e-Ra

ted

Gene

rato

r Set

Alte

rnat

or

Peak load (kVA) compared to prime kVA rating < 80% 80%<x<100% ≥100%

Avge load (kVA) compared to prime kVA rating < 60% 60%<x<70% ≥70%

Engi

ne

Peak load (kW) compared to prime kW rating < 80% 80%<x<100% ≥100%

Avge load (kW) compared to prime kW rating < 60% 60%<x<70% ≥70%

Alte

rnat

or Continuous load (kVA) compared to continuous rating < 80% 80%<x<100% ≥100%


Sub-Service Assessment parameter Within Limits Marginal Exceeded

3 Cont

inuo

us-R

ated

Ge

nera

tor

Engi

ne

Continuous load (kW) compared to continuous rating < 80% 80%<x<100% ≥100%

Notes for Table 3:1. All limits for a prime-rated CEPS must be satisfied, including peak load and average load, for both alternator and

engine.


Condition is assessed for HV substations and LV switchboards according to the application of criteria detailed in Table 4.

Table 4 Condition - practical assessment criteria

Condition Category

Condition Unserviceable Condition Poor Condition Fair Condition Good

Serviceability Item cannot provide power to its rated capacity

Item can provide power



Maintenance (oil-sampling)

Immediate works to address dangerous levels of oil conductivity, acidity or dissolved gases are required

Remedial works or monitoring is recommended.

No remedial works for oil conductivity, acidity or dissolved gases are recommended.

Oil leaks Major oil leaks Minor oil weeps No oil weeps/leaks

Functional cable rings

HV cable ring not connected due to poor condition of substation

HV cable ring connected

HV cable ring connected

Floor hazards Floor tread plates missing from cable trenches

Floor tread plates cover all holes/fit over trenches

Water in cable trench

Cable trench contains water

Cable trench dry at inspection

Warning labels (quantity is irrelevant to condition)

Warning labels illegible

Warning labels new or faded


Condition Category

Condition Unserviceable Condition Poor Condition Fair Condition Good

Structure - Doors Doors insecure/cannot be opened

Doors securely held and able to be opened/closed easily

Structure - Equipotential bonding (quantity is irrelevant to condition)

Existing earth straps have pulled out of doors

Existing earth straps are attached securely

Structure – emergency lights

Emergency lights do not work (one or more)

Emergency lights all work

Substation footings(Kiosk substations only)

Footings are unstable

Footings appear badly cracked or crumbling

Footings do not appear badly cracked or crumbling

LV power meters (LV switchboards only)

Meters unreliable Meters reliable


Section 01 – Description

This section is generally written last. It forms an executive summary.

What to report:

1.1 Overview –

What is the high level overview of the base’s electricity network? E.g.:

o How many sources of supply? What voltage?o How many intake substations?o What does the HV distribution look like?

E.g. Four ring mains with thirty substations (11/0.415kV) distributed around base, with power factor correction included at each substation

o What generation capacity supports the network? E.g. CEPSo What generation capacity supports individual loads? E.g. LEGs

Follow with a detailed description of the network.o Where and how are the supplies connected into the base?o How old are the connection points?o How many other customers are connected to the DNSP’s feeders to the base?o What redundancy is there in the physical arrangement of the incoming supplies i.e.

in the DNSP’s network?o Power factor correction – is it installed? Does it work?o Describe the HV cable network topology – What risks to Defence are inherent in the

HV network configuration? E.g. Can a single point of failure result in a long power outage?

o What backup options are provided? What risks are presented by the lack of backup or the time taken to obtain backup power?

o If relevant, include: “Airfield lighting completes the electrical infrastructure at <RAAF Base XXX>. As it is outside the scope of the HV infrastructure investigation, it is not discussed further.”.

Detached properties:o Include a general description for each property

E.g. Where is it? What is the land area? Who uses it? For what purpose?o How are the detached properties supplied with power?

E.g. DNSP-owned pole transformer outside property with LV feed to siteo What redundancy exists in their power supplies? E.g. LEGso Are there inherent risks to Defence? E.g. No LEG for a RADAR site?


Section 2.0 Incoming Supply

Some terms:

Electricity supplier/distributor = DNSP = Distributed Network Service Provider = the electricity supplier who owns the distribution network / power linese.g. Ergon; Energex; Power and Water Corporation (PWC); Western Power etc.

Electricity retailer = the company which bills Defence for the electricity usage = sometimes different to the energy supplier or sometimes the same companye.g. Energy Australia; Origin Energy; Synergy; Alinta; Perth Energy; ERM Power

Contestable site = a site which purchases power from an agency other than the local energy distributor

Authorised demand (Ergon term) = the maximum amount of power permitted through the connection point. The authorised demand is the network capacity reserved exclusively for the base. It is defined by the base’s connection agreement / electricity supply contract. (Other DNSPs should have a similar term in their contracts.)

Contracted Maximum Demand (CMD) (Perth Energy term) = equivalent to Ergon’s authorised demand

Data required:

Physical arrangement of feeders Physical capacity of feeders (DNSP-owned) Physical capacity of feeders (Defence-owned)

– cable installation conditions for derating and cable construction for capacity Total peak demand on feeders Demand of other customers Demand of Defence base Minimum historical power factor of base Historical harmonic content of base Condition reports or visual inspection (Defence-owned feeders) Is it a contestable site? GFIS (cable route records) Connection agreement (authorised demand and guarantee of backup power)

What to report:

2.1 Description –

What is the physical arrangement of each incoming supply? Include cable types and size if available.(E.g. sourced from DNSP’s zone substation ABC, leaves zone substation by buried cable of construction X and capacity X, transitions onto overhead lines of construction Y and capacity Y, overhead feeder route is through industrial area xyz, total route is x km to the base, where it transitions onto Defence-owned underground cable of construction Z and capacity Z to enter the intake substation.)

How many customers are supplied by each DNSP feeder to the base? What is the redevelopment history of the supplies to the base? (optional) Is there power factor correction within the Defence network?

The following template sentence may be useful: “Power factor correction units, intended to


optimise the sizing of the electrical infrastructure, reduce the current drawn through the connection points and improve the site power factor, is … e.g. due to be installed by <date> / currently installed at <location> / etc.”

Include a summary diagram of the incoming supplies, especially if it is a complicated arrangement.

2.2 Capacity –

Analyse capacity of each incomer, by owner. What is the utilisation of each DNSP network feeder?

o What is the existing installed capacity of each DNSP-owned incomer to the base?N.B. DNSPs sometimes set upstream protection settings above the physical capacity

rating of their distribution cables! It is best to find out both the upstream protection settings and the rated physical capacity.If this is the case, include the risk to Defence. There is an example in Oakey’s report, par. 60, “… the cable has a potential vulnerability to small overcurrents (e.g. caused by high impedance faults), which could overload the feeder with resultant cable failure.”

o What is the existing historical peak demand on each DNSP feeder from all customers?

o Hence, what is the utilisation (opposite to spare capacity) in the DNSP network? What is the spare capacity in each Defence-owned incoming feeder?

o What is the existing installed capacity? Include assumptions for cable derating and capacity if necessary. (See

example Table 8 in Oakey’s report.)o What is the existing peak demand of the base?

Include its derivation in reporto Hence, what is the spare capacity in the Defence incomers?

What is the risk to Defence from the amount of spare capacity:o on the main feeder?

Is there guaranteed spare capacity reserved for the base or is supply of load growth dependent on the discretion of the DNSP?

If the spare capacity is limited, what is the limiting factor? Consider discussing by how much the spare capacity could increase if the existing limiting factor were eliminated? How major would the works be? Expensive? Difficult? Should Defence be considering doing this?

o on the backup feeder? E.g. Is its installed capacity less than the base’s demand? During a blackout

on the DNSP’s main feeder, will Defence risk losing all operations, some operations, essential operations, etc.? Is the risk reduced because LEGS will support essential loads? Is there a CEPS to reduce the risk? Is the risk unmitigated because the CEPS is inadequate / unreliable?


Example incomer capacity assumption table

Table 8 Defence-owned Incomer Cable Ratings (Example from Oakey’s Table 8)

Item ISS1 Incomer ISS2 Incomer

Cable Number (DSR 3.14)

E02 E03

Cable Description Ergon point-of connection 1 Ergon point of connection 2

To ISS1 (Building A103) To ISS2 (Building C52)

Voltage Rating Assumed 6.35/11 kV(Unknown if cable rating is 19/33 kV, suitable for future 33 kV)

6.35/11 kV

Cable Type (DSR 3.14)

400 mm2 Copper, XLPE/ High Density Polyethylene (HDPE), 1 x 3-core

240 mm2 Aluminium, XLPE, 1 x 3-core

Length (DSR 3.14)

500 m 270 m

Installation conditions

Descends pole, then buried direct in bedding material, except in conduit for road crossings. Limiting factor is installation in conduit.Conduit depth: 1,650 mm (1,000 mm to top conduit then 200 mm between conduit edges thereafter).No. of cables per conduit: assumed single.Total number of HV power circuits in trench: 3 (cables E02, E41 and E59).(DSR 3.14)

Descends pole, then buried direct, but assumed to cross roads in conduit. (DSR 3.14)

Assumed depth of lay: 1,000 mm.

Assumed no. of parallel circuits: 1 road-lighting circuit

Remarks Datasheet for XLPE/HDPE cable is unavailable, so estimate is based on XLPE-insulated, PVC-sheathed cable and XLPE/HDPE triplex cable.Derating factor of 0.81 for potentially 4 circuits (1 future) under road or 0.85 for 3 existing circuits. Additional derating factor of 0.96 for depth of lay.Total derating 0.78 or 0.82.

Estimate is based on XLPE-insulated, PVC-sheathed cable.

Derating factor of 0.91 for 2 circuits.Additional derating factor of 0.99 for depth of lay.

Total derating 0.90.

Estimated Capacity In the order of 400 to 440 Amps, Based on Olex’s HV catalogue (DSR 3.62)

284 Amps,Based on Olex’s HV catalogue (DSR 3.62)

Site Maximum Demand

4.70 MVA (247 A) 4.70 MVA (247 A)

Estimated Utilisation Full site load operated through either ISS1 incomer or ISS2 incomer.i.e. 62% utilised

Full site load operated through either ISS1 incomer or ISS2 incomer.i.e. 87% utilised


2.3 Condition –

DNSP-owned assets are NOT assessed for condition.o If applicable, include: “The incoming power supplies, upstream of the points of

connection, are owned and maintained by DNSP, <name>, and as such were not assessed for condition.”

Defence-owned incomers ARE assessed for condition. Overhead lines: If no other information is available, make an assessment on a visual check

for damage, deterioration, termite infestation and issues with vermin. Underground cables: If a cable cannot be regarded “As New”,

o When was it last redeveloped? o Can it be assumed that it was in good condition when laid? o Can it be assumed that nothing has disturbed it since installation? o Is its expected life at least, say another 20 years, provided it remains within capacity

limits? o Cable markers – are these in suitable condition?o If so, then it can be assessed as good condition.

Are any (condition) risks to Defence obvious?

2.4 Compliance –

For DNSP-owned assets, compliance is assessed against:o MIEE 2011o National Electricity Rules

For Defence-owned assets, compliance is additionally assessed against:o Australian Standards.

MIEE 2011 – o Physical arrangement - Does MIEE require at least two incoming feeders to this

establishment? Is the arrangement compliant? If not, what is the risk to Defence? Risks to Defence –

Are multiple supplies independent to some degree? E.g. do they have different routes from the zone substation to the base.

What availability does the backup feeder have? Is the backup feeder available all the time? Is it available only by switching? How long would it take to come online? Is its availability guaranteed, or subject to the DNSP’s sole discretion to provide backup power by load-shedding other customers?

o MIEE capacity – MIEE 2011 requires generally that incoming feeders are sized for the ultimate base load – Each feeder is individually compliant or non-compliant - Can it be assumed that the capacity of the second feeder has been approved by DEEP, if its capacity is less than the ultimate base load?

o Contestable sites – MIEE requires that contestable sites comply with the National Electricity Code.

National Electricity Code – o Harmonic content

Are the harmonics generated by the site acceptable to the DNSP? For info only: In Perth, the compliance limit is 8% total harmonic distortion

(THD); Western Power’s planning limit is 6.5%.o Power factor


o What is the risk to Defence of non-compliance? Higher costs, energy losses, disconnection from DNSP network, etc.

Aust. Standards – o Physical installation (depth of lay and clearances from other services) -

1. If it is reasonable to assume that buried cables have remained undisturbed since installation, then it can be assumed that they remain compliant with Aust. Standards in respect to their physical installation.2. If overhead lines are identical to DNSP lines, they can likely be assumed compliant.

o Cable route records – AS 2067 s4.2.9.1(a) requires that underground cable routes are ‘appropriately identified’ – hence, the GFIS route is compliant or non-compliant. If non-compliant, what is the risk to Defence?

Neither MIEE / NEC / AS – o Reliability of supply - Is there a negotiated connection agreement? Does it stipulate

an authorised demand? If not, is there another method by which a minimum amount of power is guaranteed to be available for the base?

Note: The absence of a connection agreement does not mean it is non-compliant. What it does mean is that in the issues register, negotiations should be recommended in order to guarantee a minimum level of power supply, to secure exclusive access to spare capacity in the DNSP feeder if the base is entitled to it, to avoid risking power outages, and to guarantee a particular level of emergency / backup power.

Do any other risks arise from the physical arrangement or compliance of the feeders?


Section 3.0 – Intake and Primary Switching Stations

This section includes primary distribution, which is essentially all HV switchboards and ISS buildings.

Exclusions - Other than a CEPS HV switchboard and its auxiliary power supply (trip/close batteries), everything associated with a CEPS is excluded from this section. The CEPS and its associated components are covered within the CEPS section. E.g. CEPS building, control room, generator control system, batteries for genset starting system, adequacy of fuel supply, load-shedding system etc.

Data required:

General installation details (sketch of floor plan, checklist, photos = generally sufficient) Site SLD Switchboard maximum demand

o Metering data for 12 months, if available, ORo Site demand ANDo Logged switchboard currents

Switchboard capacityo HV switchboard nameplate, ANDo Busbar rating, ANDo HV circuit-breaker ratings, ANDo Protection CT ratios (if possible)

Overcurrent protection relay models/types, for each tier Protection relay test records Oil dissolved gas analysis (DGA) test records, for oil-filled switchgear Checklist and photos

(Note: A photo of each compartment of each tier can be a lifesaver later, depending on what issues are found.)

HV switchboard drawings (Note: Required only if capacity is unavailable from nameplates, or if there are particular condition/compliance issues with switchboard.)

Auxiliary equipment details, if there are particular condition/compliance issues

What to report:

3.1 Description –

Note: the level of required detail in the Description section will differ, depending on whether there are any major condition issues or non-compliances needing later analysis.

What are the salient features of the intake substations and HV switchboards? E.g.o At what voltage is incoming supply? o At what voltage are outgoing feeds?o How many HV switchboards are in the ISS / CEPS?o How are they configured? Bus-ties? Number of feeders?o How is auxiliary power provided? (E.g. 240V UPS? 48V Batteries?) (optional)o What provision has been made for future expansion? On the switchboard? Space

in the building? (optional)


How are the different HV switchboards connected together?o Ring mains?o Interconnectors?o How many distribution substations?

3.2 Capacity –

What is the utilisation on each HV switchboard?o What is the maximum demand on the switchboard (usually site demand)?

Explain / justify the maximum demand used Has recorded current for a consecutive period of at least 12

months as per MIEE 2011 preference been used? If not, what was used instead?

(E.g. a combination of temporary load logging and DNSP-provided annual maximum demand figures.)

What clarifications for temporary load-logging are necessary?E.g. how was it done? How reliable are the results? Do the results need adjusting for the season of the year? Were any loads missed? If so, are the missed loads significant? Were the currents logged simultaneously? If not, what adjustment needs to be made to the maximum demand?

o Include a graph of the logged currents. See example below.o In order of preference, baseline the site maximum demand against:

1. Busbar rating, or if unavailable then 2. Incomer circuit-breaker rating, or if unavailable then 3. Incomer protection CT size.

o What is the limiting factor on utilisation? If the busbar size is significantly different to the other ratings, include

clarification. An example from Oakey’s report par. 162-165 follows:… The busbar rating of the HV switchboard at ISS2 is 1,250 A, from the switchboard ‘As Constructed’ drawings (DSR 3.50). The switchboard utilisation, on first appearances, is therefore considered to be 20 per cent. … It should be noted that the capacity of each switchboard feeder is limited according to each individual panel’s circuit-breaker size, the protection CT ratio installed in the panel, and the protection setting. Each circuit-breaker, including the incomer, is rated for 630 A. On every panel, the protection settings are currently 70 per cent of each primary CT ratio, which confirms the switchboard baseline is within limits to meet current demands. ... It is noted that, should the load increase to approach their ratings, the protection and metering CTs could be replaced with equipment rated up to the size of the circuit-breakers.… [Based on the busbar capacity, but] noting that the CTs and circuit-breakers are rated less than the busbar capacity, the capacity baseline of ISS2’s HV switchboard is considered to be within limits to meet current demands with 80 per cent capacity remaining.

Is there a significant risk to Defence? E.g. Is 99% of the CT protection rating currently being utilised?

What is the risk to Defence? Are any utilisations (busbar, incomer or CT’s) marginal or exceeded?

o E.g. (from Oakey report par. 168)If the ultimate base load of 350 A (DSR 3.43) is ever reached, ISS2’s switchboard capacity will technically remain within limits with 28 per cent of the busbar rating used. However, as the switchboard will be operating at 88 per cent of the incomer’s CT rating, it would be prudent to consider replacing the CTs if the projected loads are revised higher.

3.3 Condition –

Use the inspection checklist and a keen eye. What condition issues are there with the:o ISS buildings?


o HV switchboards? Note:

o The level of detail required depends on the final assessment outcome.o Maintain a keen eye because not every possible condition issue has been

captured in the checklist (such as, self-powered relays being used in a HV switchboard more suited to externally-powered relays).

What risks are presented to Defence? o E.g. Is the condition issue likely to cause failure of the component? Will the ISS

become unserviceable? How high is the risk?o E.g. Water in cable trenches: will degrade insulation, decrease service life, rust

cable supports in the trencho Etc.

The key is to articulate both the outcome of the inspection, and discuss in detail the risk/issue supporting the final assessment.

3.4 Compliance –

Compliance is assessed against:o AS/NZS 3000:2007 (including Amendments 1 and 2);o AS 2067-2008 (including Amendment 1); ando MIEE 2011

Include the following paragraph:<Name which intake substations and CEPS HV switchboards> were inspected by an electrical engineer and detailed checklists (DSR 3.xx) were evaluated for compliance to Australian Standards and the MIEE. Inspections of the HV switchboards were facilitated by a qualified electrician from the CMSC.

What are the major compliance issues against Australian Standards? (Use the checklist.) What are the major compliance issues against MIEE? (Use the checklist.) The following 2 template paragraphs may be useful:

o “The highest risks are associated with …abc… . Although these issues are more than likely caused by condition factors, they are also non-compliant to Australian Standards as AS 2067 section …pq… requires that ‘…xyz…’.”

o “All the identified non-compliances are listed in the Issues Register (refer to Appendix A). Key non-compliances to Australian Standards are: …abc… . Key non-compliances to MIEE are: …xyz… .”

What is the risk to Defence presented by the non-compliances?


REQUIRED logged current graph:

Figure 1 HV ring currents logged at ISS1 (Example from Oakey Figure 1)


Section 4.0 – Ring Mains

This section includes all the HV interconnectors and ring mains cables. HV cable labels are included in this section, not in substations.

Data required:

Site SLD Site maximum demand (for interconnector) Individual ring mains maximum demand

o Metering data for 12 months, if available, oro Logged switchboard currents

Protection reports (assessed cable capacities and required protection settings) Protection relay test records (actual overcurrent protection settings) Cable schedules Installation details (derating) Cable route drawings / GFIS (parallel cable routes → cable derating) Photos

o Cable typeso Cable labels

Cable capacityo Cable datasheets, if available, oro Industrial cable catalogues otherwise (capacity tables)

What to report:

4.1 Description –

Overview of the HV cable network topologyo e.g. ring names, how many spurs, types of loads on each ring, how many

substation loads in total, are loads connected to the interconnector, etc. How is load transferred between HV switchboards?

o Via ring mains or via interconnector? Overview of history / how much is known about the cables

o Sizes/types are known or uncertain?o How old?o Routes are well understood or vague? Estimate a percentage accuracy of GFIS.

If necessary, what documents were used in lieu of a cable schedule?

4.2 Capacity –

Potholing - If relevant, include this template paragraph for potholing:Physical cable capacity is affected by cable size and insulation type, and installation conditions (e.g. buried direct/installed in conduit, depth of burial and number of cables grouped together). The cable installation conditions for <site name> are understood to vary across the site, but remain generally unknown, without an ‘As Constructed’ cable schedule or updated GFIS. Potholing to determine installation conditions was not carried out, as there would have been limited benefit of potholing only a sample of locations.

Estimate physical cable capacities (see example summary table from Oakey’s Table 17)

o Are there existing estimates of cable capacities? Are they reliable? Note: Some previous base HV reports have not included any derating, nor

given any reason for ignoring derating. Also, especially when site documentation is wrong, previous reports have used erroneous cable types, and therefore their capacities are invalid. Therefore, it may not be wise to reuse previously reported capacities without giving them a (thorough) sanity check first.

o What are the installation conditions? Explain assumptions (assumed installation conditions and therefore

derating)o What are the cable sizes and insulation types?

Explain method and assumptions e.g. cable sizes were noted from cable labels; labels either end were analysed for consistency and compared to the visible cable insulation types, to any available cable documentation and to network drawings.

Note: doing a comparison of cable labels OFTEN finds inconsistent labels either end of the same cable, wrong records, errors on cable schedules and sometimes labels different to the visible insulation type, even 2 or 3 different cable labels on the same end of a cable or even cables installed side-by-side which are obviously different physical sizes but are labelled as the same. All these problems = add to the issues register = advise/discuss the risk to Defence.

Note: A cable label different to the visible cable type is not always useless; it could mean that the cable run has been almost totally replaced but the new cable was joined outside the substation to a tail of the old cable, to avoid re-terminating. In this case, the apparently incorrect cable label is a clue to a joint outside the substation.

o Hence, what is the estimated capacity? Based on what?

E.g. from industrial catalogues, based on the above assumptions for installation conditions and cable sizes and types

What is the level of risk to Defence, or possible negative outcomes, from any assumptions, generalities or unknown cable sizes/types.

o Example risk paragraph from Oakey’s report par. 242:The risk presented to Defence from unknown cable types is not only that the current carrying capacity of those cables is unknown, leaving them potentially unprotected from overload, but also that engineering analysis of the HV network cannot be completed without assuming a cable type, which affects the reliability of any HV protection study, fault level study, load flow analysis, etc. This in turn impacts upon the ability of the network operators to understand the network, to optimise the current flow in the network and hence minimise power losses, and to ensure that the equipment is adequately protected from overload or damage. Subsequently there are potential risks to personnel safety and to Defence of shortened cable life or should equipment fail, of extended power outages. The cables presenting the highest risks in this regard are mentioned specifically in this analysis, but nevertheless the size and type of each unknown cable are recommended to be confirmed.

What is each cable’s utilisation?

o

o Note that both protection setting and installed cable capacity need to be checked!

o Why is the protection setting preferred? Assuming that voltage drop is the limiting factor on cable capacity, the

installed capacity is misleadingly high. Presumably a protection study was done before the settings were installed.

Presumably the protection study recommended a setting appropriate to limit voltage drop.

Presumably the protection setting has been installed at the permitted current-carrying capacity, rather than on a different methodology, such as being much less than current-carrying capacity but just above the maximum demand or just high enough to discriminate with downstream protection settings.

o Why is the installed cable capacity also needing to be checked? In case the protection setting happens to be higher than the installed

capacity. In case the protection study was based on erroneous cable data/ratings

(don’t laugh – this has been found to be the case previously!). In case the protection setting was installed just higher than maximum

demand or ultimate base load (but this would be very hard to prove without the original protection study report).

o Discuss ‘marginal’ and ‘exceeded’ results by exception.o What are the risks to Defence?

How certain are the assessed cable capacities? Is it known on what basis was the protection level set?

Installed cable capacity, with or without appropriate derating? Permitted current-carrying capacity, accounting for voltage drop? Ultimate base load? Maximum demand? Erroneous cable data?

E.g. from Oakey’s par. 272:The assessed cable capacities are sensitive to the assumptions made, so it is recommended that these are validated as recommended in Appendix A.

Are any cables overloaded or of marginal spare capacity? How likely are they to fail? E.g. from Oakey’s par 247:If it is not replaced, depending on how far the cable is overloaded in the future, the cable could fail or its lifespan could be shortened due to overheating.

Overall assessment: If ANY ring mains or interconnector is assessed as marginal or exceeded, so must be the overall assessment. The overall assessment is NOT an average of the cable capacity assessments.

4.3 Condition –

Include this template clarification for only having done visual inspections:Visual inspections were carried out to assess the condition of the cables. Potholing and any inspection which would have required de-energisation of portions of the electrical network and interruptions to site operations were not undertaken.

What is the basis of the condition assessment?o Age and insulation type? E.g. Paper-lead = fair, while XLPE = good?

o Documented condition assessment provided by the CMSC?o Other?o If based on cable age and type, the following template paragraph might be of

use: (based on Oakey par. 257)Provided the visual inspection did not indicate any condition issues to the contrary, cable condition was assessed based on age and type. The paper-lead cables at <site name> are estimated to have been installed from approximately <start year>, when the site began, until the early 1990’s when XLPE cables became widely used. Paper-lead cables on the site are therefore approximately 20 to <how many> years old and were assessed as being in fair condition. XLPE cables, being estimated at less than 20 years old, were assessed as being in good condition. The following exceptions were made:a. Cables replaced in the <xxx HV upgrade> were assessed to be as new. b. Where segments of paper-lead cables have multiple joints in them due to repairs, the condition was downgraded to poor, due to potential damage as a result of previous faults and stress.c. Segments containing few joins between cables of different type/age were assessed overall as the lowest constituent condition. For example, a segment containing an XLPE cable jointed to paper-lead cable was assessed overall as fair.

Include the required condition summary table. (see example below - Oakey’s report Table 20) Assessment Outcome = weighted average.

o Overall rating can be the same as, or different to, the worst cable condition.o Include the risk to Defence

E.g. of risk from Oakey par. 259 (b) Two long paper-lead sections [are] assessed as [in] poor condition in the Airfield Ring, [because they] have multiple joints in them from previous repairs. Joints in cables are one of the common failure points. However, the paper-lead cables themselves present a low risk of failure. These are assessed as a low risk to site operations as they are in a ring configuration and paper-lead cables are common in older networks.

4.4 Compliance –

Compliance is assessed against:o AS/NZS 3000:2007 (including Amendments 1 and 2);o AS 2067-2008 (including Amendment 1); ando MIEE 2011

If data was limited, the following introduction may be useful: (Oakey’s par. 268)To assess cable compliance to Australian Standards, the primary information required is physical installation conditions, cable capacities and respective protection settings, and cable records. To assess compliance to MIEE, the minimum necessary information regards cable capacities (including fault withstand levels), cable labelling, and cable type.

Include a statement about how the analysis was able to be done on the limited available information.

o E.g. from Oakey par. 269Potholing of the cables was not undertaken as there would have been limited benefit from potholing a sample of locations across the site. The installation conditions and cable types and thus the cable compliance have been estimated from the available data which was: a. Cable type and labelling at substations, by visual inspection (DSR 3.xx); b. <list other available documentation> (DSR 3.xx); and c. GFIS cable route records (DSR 8.xx).Analysis of this data is consolidated in DSR 3.xx. Some cable types remain unknown, either because cable types were not visible or conflicts between the available data could not be resolved. Site inspections of the cable labels were facilitated by a qualified electrician from the CMSC.

AS – What are the non-compliances to Australian Standards?

AS compIiance: Installation conditionso Is enough known about the installation conditions to assess them?

If not, include the following statement:Compliance to Australian Standard requirements for minimum depth of burial and mechanical protection of buried HV cables etc. was not assessed.

Follow that statement by reporting what is known about installation conditions

AS compliance: Protectiono AS 2067 section 7.2 requires protection from ‘the effects of faults and unacceptable

overloads’.o What capacity and protection data is available to use? Is it reliable? Is it based on

assumptions? Reference the assumptions already made about cable capacity, if necessary.

o Are the cables protected? Include a table of compliance per ring main. See the example from Oakey

Table 22. Include a list of which cables in the ring mains are unprotected. See the

example from Oakey Table 23.o What is the risk to Defence? What remedial actions are required?

Is the assessment valid? Was the data reliable? Do assumptions cast doubt on the outcome? Does data need verifying? Does a protection study need revising? Do protection settings need review?

What is the risk to Defence? E.g. from Oakey par. 273The risk from unprotected cables is that a severe overload would cause immediate cable failure, leading to extended power outages and expensive repair, while prolonged slight overloads would stress the cable insulation and shorten the cable life.

AS compliance: Record of underground cable routeso AS 2067 s4.2.9.1(a) requires ‘appropriate means of identifying cable routes’ for

cables installed underground.o Markers on-site, in situ - This could be assessed in a number of ways.

Explain chosen method. Compliant or non-compliant? Previous PMCA comment: When spot checks are used as a sample to make

an overall assessment, the validity of the locations chosen must be demonstrated. I.e. How were the locations chosen?E.g. from Oakey par. 274, Spot checks were undertaken in four geographically-diverse locations, selected across old and new cables, as a sample to assess compliance generally. Findings from the spot checks are: …

o Survey data Estimate how accurate GFIS is.

Compare GFIS to any available survey data (usually BEAP commissions a survey of HV pit locations).

CMSC electricians usually know if GFIS is reliable.E.g. from Oakey par. 276, Professional surveyors were engaged to verify cable pit locations. GFIS was updated with the survey data (DSR 8.xx). It showed <…describe the results…>.

Compliant or non-compliant? Cables missing from GFIS = non-compliant Badly inaccurate route records = non-compliant Etc.

AS compliance: Overall summary – compliant or non-compliant?

MIEE – What are the major compliance issues against MIEE?

MIEE compliance: Ring configuration

o Include template sentence, if relevant: (from Oakey’s par. 277)MIEE (section 26.4.2) requires that distribution substations on a ring main system shall generally be connected to two primary nodes (i.e. <node names, for example, ISS and CEPS>), although MIEE also provides that Defence will consider approving deviations from this requirement based on an assessment of the importance or remoteness of the loads.

o Is the distribution between 2 primary nodes? Are there HV cable spurs? Has MIEE approval been given? Can it be assumed as given? On what evidence?

o Compliant or non-compliant?o Note: If approval for spurs is assumed to have been granted, then assess

network as compliant.

MIEE compliance: Minimum capacity and insulation typeo Include template sentence: (from Oakey’s par. 278)

MIEE compliance requires that cables be sized generally for a minimum fault level of 250 MVA for one second and for a minimum capacity of 4 MVA when all derating factors are applied.

o Fault level (min. 250MVA for one second) Are cable fault withstand values available from datasheets? If datasheets are unavailable, what assumptions can be made?

E.g. light- or heavy-duty fault rating for cable screen? If datasheets are unavailable, what are the industry catalogue fault

withstand levels for light-duty and heavy-duty screens? Are either of the catalogue screen ratings compliant to MIEE?

If neither → non-compliant to MIEE;If one is → there’s a possibility of MIEE compliance. (E.g. Oakey par. 279)Cable datasheets containing fault withstand levels for the existing cables were unavailable. Hence, the ability of the network cables to withstand the MIEE fault level could not be verified. Based on industry catalogues (DSR 3.xx), a heavy-duty or high level of fault screen rating would have to have been adopted for the cables to comply with MIEE in this respect. Without actual datasheets, it is unknown what ratings are installed.

What is the risk? - Can Australian Standards compliance be proven? (E.g. Oakey par. 279)As the highest fault level within the site (xx kA – DSR 3.xx) is less than typical light-duty screen ratings, the ability of the cables to withstand a prospective fault is considered compliant to Australian Standards, even though it cannot be verified for MIEE compliance.- If AS compliance is ok → then risk is negligible, provided compliance is maintained (E.g. Oakey par. 279)Whilst the prospective fault level on the site remains in the order of xx kA, the risk to Defence of not complying with the MIEE fault rating is negligible. However, should the prospective fault level increase over time, beyond the fault withstand level of the existing cables, there is a risk of cable failure under fault conditions. Under this future circumstance, the replacement of cables with those of higher fault ratings would require consideration.- If AS compliance is unproven → what’s the risk? Do the cables need replacing? Does fault-limiting equipment need installing? Do protection settings need review?

o Capacity (min. 4 MVA)

MIEE compliance: Spare capacityo Include template sentence:

MIEE compliance requires that 60 per cent of the cable capacity is not exceeded.o xxx

MIEE compliance:

Example cable capacity table:

Table 17 Ring mains cable capacities (Example from Oakey’s report Table 17)

Ring Installed cable types1 Assumed derating / Assumed installation conditions

Estimated Capacity

Lowest Capacity of the Ring

Support

150 mm2 Cu XLPE

In conduit, Buried at 0.8 m, No derating for grouping

310 A

235 A150 mm2 Cu PLYSWA

150 mm2 Cu PLYSWA 235 A120 mm2 Cu XLPE 276 A150 mm2 Cu XLPE (3x1c) 310 AUnknown size/types betweenSubstation 11 – 12,Substation 12 – 23,Substation 23 – ISS2

Unknown

Domestic

120 mm2 Al Triplex (assumed XLPE, based on date of installation)

Buried direct in ground at 0.8 m, No derating for grouping(or In conduit, Buried at 1.25 m,4 grouped cables spaced at 0.2 m i.e.0.95 & 0.76 derating factors on 218 A)

262 A(or 157 A)2

155 A70 mm2 Cu PLYSWATBC4

150 mm2 Cu PLYSWA

In conduit, Buried at 0.8 m, No derating for grouping(or Buried direct, 3 grouped cables spaced at 0.3 m, depth of 1.75 m i.e. 0.81 & 0.94 derating factors on 280 A)

235 A(or 213 A)3

150 mm2 Cu XLPE


310 A120 mm2 Cu PLYSWA 215 A70, 95 or 120 mm2 Cu PLYSWA(cables with contradictory labelling)

155, 185, or 215 A

240 mm2 Al XLPE 316 AUnknown size/types betweenSubstation 1 – Possible joint en route to Substation 2

Unknown

Technical

150 mm2 Cu XLPE


310 A

120 A70 mm2 Al PLYSWA

70 mm2 Al PLYSWA 120 A185 mm2 Al Triplex XLPE 275 A150 mm2 Cu PLYSWA 235 AUnknown size/types betweenSubstation 20 – 17Substation 05 – Joint 03

Unknown

Airfield

150 mm2 Cu XLPE


310 A

125 A50 mm2 Cu PLYSWA

240 mm2 Al XLPE 316 A50 mm2 Cu PLYSWA 125 A185 mm2 Al XLPE 272 A120 mm2 Cu PLYSWA 215 AUnknown size/types betweenISS2 – Joint 7 Unknown

Notes for Table 17:

1. Cables are 1 x 3-core, unless noted otherwise. The limiting cable capacity is shown in bold.

2. As this cable has a low capacity and it is also an exit cable from ISS1, approximate derating has been estimated based on ‘For Construction’ upgrade drawings.

3. As this cable is rated close to the protection setting, approximate derating has been estimated based on ‘For Construction’ upgrade drawings.

4. Contradictory cable labels put the cable capacity in doubt.

REQUIRED cable utilisation table:

(N.B. 1. Add a column for physical capacity of each cable if it is not included in a cable capacity table.

2. Change Note 2 as necessary, or if need be, include two columns for Estimated Utilisation (to show a difference between the ‘installed cable capacity’ utilisation and the ‘protection setting’ utilisation if that is needed at your site).)

Table 18 Estimate of loading on HV cable rings (Example from Oakey’s report Table 18)

Ring Max. Ring Current1 Estimated Utilisation2 Capacity Assessment

Support 77 A 33% Within limits

Domestic 83 A 54% Within limits

Technical 124 A 103% Exceeded

Airfield 18 A 14% Within limits

Note:

1. DSR 3.56 – Logged Current Demands, increased by 20 per cent for summer loading.

2. Maximum ring current compared to installed cable capacity.

REQUIRED condition summary table:

(A ‘segment’ is taken to be a whole cable run between 2 substns. It is not between 2 joints per se.)

Table 20 Condition summary - HV rings and Interconnector (Example from Oakey’s report Table 20)

ConditionSupport Ring

Segment Qty.

Domestic Ring

Segment Qty.

Technical Ring

Segment Qty.

Airfield RingSegment

Qty.

Inter-connector Segment

Qty.

Total

As New 4 0 3 1 N/A 8 30%

Good 1 2 2 1 N/A 6 22%

Fair 1 4 2 1 N/A 8 30%

Poor 0 0 0 2 N/A 2 7%

Unknown (Unable to assess)

2 0 0 1 N/A 3 11%

Total No. Segments 8 6 7 6 N/A 27 100

%

Overall Rating Fair1,2 Fair3 Fair4 Poor5 N/A6 Fair Overall

Notes for Table 20:

1. Reason for unknown cable condition………


3. Reason that a partially unknown cable can be assessed as fair………..

4. Reason that a partially unknown cable can be assessed as fair………..


6. No interconnector cable is installed at <site name> currently.

REQUIRED compliance table – cable protection

(adjust table as necessary to suit available data)

Table 22 Protection settings for HV ring mains (Example from Oakey’s Table 22)

Ring Assessed Cable Capacity

Proposed Setting from GHD Protection

Report1

ISS1 Protection

Setting

ISS2 Protection Setting2,3,5 Protected?

Support235 A

(150 mm2 Cu PLYSWA)

275 A

(120 mm2 XLPE)

Unknown6

0.7 of CT secondary current,

equivalent to 280 A

No

Domestic 155 A

(70 mm2 Cu PLYSWA)

TBC4

210 A

(120 mm2

PLYSWA)


equivalent to 210 A

No

Technical 120 A

(70 mm2 Al PLYSWA)

235 A

(150 mm2

PLYSWA)


equivalent to 210 A

No

Airfield125 A

(50 mm2 Cu PLYSWA)

125 A

(50 mm2 PLYSWA)


equivalent to 140 A

Yes (ISS1)

No (ISS2)

Notes for Table 22:

1. DSR 3.43 – GHD Protection Philosophy and Grading Scheme October 2010.

2. DSR 3.54 – Site Investigation Photos.

3. DSR 3.48 – ISS2 Protection Relay Service Report.

4. DSR 3.65 – Cable Analysis Spreadsheet – Contradictory cable labels put the cable capacity in doubt.

5. Note inconsistent ring mains labelling on the switchboard. The ring mains descriptions nominated in the above table are consistent to the substation numbers labelled on the ISS2 switchboard, rather than the ring mains labelling.

6. The protection settings for the cable ring mains would have been set at ISS1 during the HV upgrade Stage 1, but the actual settings are unavailable to date. Presumably the GHD proposed settings have been used.

REQUIRED compliance table - unprotected cables:

(adjust table as necessary to suit available data)

Table 1 Unprotected ring mains cables (AS non-compliant) (Example from Oakey’s Table 23)

Ring Installed cable types Segment Assessed Cable Capacity

Highest Protection

Setting

Support1

150 mm2 Cu PLYSWA

Joint 15 – Joint 14

235 A

280 A (ISS2)

Between two potential joins in Substation 03 – Substation 22 route (In doubt, could be XLPE)

Unknown size/typeSubstation 11 – 12,Substation 12 – 23,Substation 23 – ISS2

Unknown

Domestic2

120 mm2 Al Triplex (assumed XLPE)

ISS1 – Joint 16262 A

(or 157 A TBC)5

210 A (ISS1 & ISS2)

70, 95 or 120 mm2 Cu PLYSWA

(cables with contradictory labelling)

Substation 02 – 14,

Substation 14 - 13155, 185, or 215

A6

Technical370 mm2 Al PLYSWA Substation 08 - 04 120 A

235 A (ISS1)Unknown size/type Substation 20 – 17 Unknown

Airfield4 50 mm2 Cu PLYSWA

Joint 18 – Joint 08,

Joint 09 – Substation 15,

Substation 15 – Joint 12,

Joint 12 – Joint 13,

Joint 13 – Substation 16

125 A 140 A (ISS2)

Notes for Table 23:

1. In the Support Ring, note that 120 mm2 Cu XLPE has an assessed rating of 176 A. As the protection setting is only slightly higher, 180 A, this is considered protected because the Australian Standards ratings are necessarily conservative.

2. In the Domestic Ring, an unknown cable type between Substation 1 and a possible joint en route to Substation 2 is considered protected, because it is expected to be either 120 mm2 or 150 mm2 copper, so compliant regardless of whether it is PLYSWA or XLPE.

3. In the Technical Ring, an unknown cable type between Substation 5 and Joint 3 is expected to be 150 mm2 copper, but either PLYSWA or XLPE. It is therefore assessed as protected.

4. In the Airfield Ring, the indeterminate cable type between ISS2 and Joint 7 is either 120 mm2 Cu XLPE or 150 mm2 Cu XLPE, so is assessed as protected.

5. As this cable has a low capacity and it is also an exit cable from ISS1, approximate derating for cable grouping and depth of burial has been estimated based on ‘For Construction’ upgrade drawings.

6. Contradictory cable labels put the cable capacity in doubt.

Section 5.0 – Substations

Substations includes all substations components except the main LV distribution board itself. ‘Substations’ includes the HV and the LV switchrooms if they are indoors, whether or not the LV switchroom is attached to the HV switchroom. This delineation was used in the past so that whether the main LV distribution boards are included or excluded from BEAP scope, the substation building is assessed as a whole unit in the substation section.

HV cable labels are included in the HV ring mains section, not in substations.

Section 6.0 – LV Switchboards

The LV switchboards section includes only the main distribution board. The room in which it is housed is included in the substation section, not here at LV switchboards.

Metering – what was available? Are the meters known to be unreliable? Are there risks because the data is instantaneous not historical?

Metering – are the meters ‘intelligent’? why / why not is metering data available from a comms network (DESN or PCMS)? At a very high level, what works would be required to implement ‘intelligent metering’ connected to a network so that it can be successfully remotely monitored?

LV cabling, labelling, tidiness etc. How adequate is the ‘form’ of construction (compartmented construction)?

Section 7.0 – LEGS

Obtain information from the maintenance mechanic/diesel fitter and/or maintenance electrician as to the reliability and condition of the generators. (Confirm anecdotal information by email / record of conversation.)

Be on the lookout for concerns about unreliable starting, overloading, unavailability of spares etc.

Collect enough information to fill out details of the following table

Copy Harman & Oakey

Section 8.0 – CEPS

Section 9.0 - CPS

brief for beap electrical investigators / engineers · web viewall limits for a continuous-rated...

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