application guidelines secondary wiring ais - gis

1(29) Doc. no. Rev. ind. 1.0 Date 20.03.2008 Issuer Bernhard Deck Dept. PPMV-DA Phone +41 58 5867037 E-mail [email protected] Template 1MRS170791

Application Guidelines

EMC proof secondary wiring AIS – GIS switchgear

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Filename: Application Guidelines Secondary wiring AIS - GIS .doc; Printdate: 20/03/2008 13:50:00; Savedate: 20/03/2008 12:49:00; Owner: Bernhard Deck PPMV - DA

1 Introduction Secondary Cabling Secondary Cabling has an important role to guarantee the EMC proven function of the panel. It is important that the cabling is done from technicians with adequate skills and being able to understand the problematic. This is also important because the resulting product is a customized product and cannot be type tested. On the opposite the used devices and functions are type tested and fulfilling all the standards as required. They are tested with standard cables connected to, and verified with “standardized disturbances”. In case the cabling is done wrong the required robustness maybe not sufficient. As a result failures may spurious occur, and even damages of devices and functions, also at a later stage. This is valid also for non ABB products used in ABB switchgear, or ABB Products in non ABB switchgear. Since the secondary cabling do not end in the secondary compartment it is same important to follow same rules when installing switchgears on site. It is important that before commissioning installed switchgears some basic investigations on the cabling and cable types has to be done. If the following guidelines are followed, EMC robust customized switchgear will leave the factory and is getting less sensitive in the harsh environment installed. This finally improves the quality and the lifetime of the products, which is what a customer is expecting when choosing ABB. Thanks for the input to this document from Paul Rudolf, Sven Wehrmann, Werner Ebbinghaus and Zavoche Houchangnia.

2(29) Doc. no. Rev. ind. 1.0 Date 20.03.2008

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For Internal Use Only

List of Contents

1 Introduction Secondary Cabling....................................................................................1

2 Introduction on EMC......................................................................................................4 2.1 EMC in Switchgears............................................................................................5 2.2 Earth Points / Earth System.................................................................................6 2.3 Cable Shields and Wiring....................................................................................9

3 Standard switchgear combinations..............................................................................10 3.1 AIS with CT ......................................................................................................10 3.2 GIS with CT ......................................................................................................10 3.3 AIS with Sensors ...............................................................................................10 3.4 GIS with Sensors ...............................................................................................10

4 IED installation ............................................................................................................11 4.1 Installation requirements for protections relays ................................................12 4.2 Earth screw Power Supply REF542plus............................................................13 4.3 Recommendation for digital input delay setting of an IED (REF542plus) .......13

5 Cable routing..................................................................................................................14 5.1 Classification of signals according to level of interference...............................15 5.2 Max. Length of control cables connected to binary inputs ...............................15 5.3 Minimisation of differential mode (DM) loops in LV compartments...............15 5.4 Wiring of external Ring CT’s and VT’s............................................................15 5.5 Treatment of spare wires of the Relay...............................................................16 5.6 Maximum length of excess wiring inside switchboards....................................16 5.7 Requirements for LV signal cables going to the REF relays ............................16 5.8 Cable entry for HV single and 3-core cables, LV cables, CTs cables...............16

6 EMC-compliant earthing of the switchgear................................................................17 6.1 Design of earthing systems with regard to touch voltage and thermal

stress ..................................................................................................................17 6.2 Bonding of earth bars in LV compartments ......................................................18 6.3 Bonding/ earthing of main switchgear earth bar (max. distance between

bonds) ................................................................................................................18 6.4 Recommendations on configuration of the switchgear earthing .......................18 6.5 Recommendation for substation earth grid construction...................................20


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7 Appendix.........................................................................................................................20 7.1 Golden Rules to avoid EMC disturbance ..........................................................20 7.2 Immunity requirements for protection relays ....................................................21 7.3 Performance criteria ..........................................................................................22 7.4 Single core cable bonding .................................................................................23 7.5 Cable Bonding different types...........................................................................24 7.6 Switchgear Earthing ..........................................................................................28


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2 Introduction on EMC Electromagnetic compatibility (EMC) means that a device is compatible with its electromagnetic environment and the equipment installed can work correctly without creating disturbances for other electrical equipments or being influenced by other equipments. An electrical device can have an uncontrolled behavior if the level of electromagnetic energy emitted from other devices exceeds the electromagnetic immunity level (its resistance) for which the device was designed, tested and approved. The different forms of electromagnetic disturbances are conducted, radiated and electrostatic discharge (ESD). These disturbances can induce some unwanted energy and/or information in the normal functionality of the device. The goal of Electromagnetic Compatibility is the correct functionality of each device in its environment and to reduce disturbances. Reduction of disturbances is the reduction of interference. For reducing different disturbances we have to reduce the source of the emission and to improve the immunity of each device that could be considered as a receiver. The energy transferred by this kind of interference is considered as disturbance. Different kind of coupling can be found:

• Conductive coupling is a direct coupling between the source of the noise and the device considered as the receiver. The transmission is created by a wire or a cable (direct contact). Also a wire is not only composed by its resistance but also has an inductance and a capacitance in parallel with R and L. This is the impedance and not only a resistance.

Z = R +jLw +1/jCw w= 2*pi*f

• Inductive coupling. Short distance between the disturbance source and the device (less than a wavelength). Inductive coupling can be produced by magnetic field which is generated by the current through a wire.

• Capacitive coupling. Short distance (less than a wavelength) between the disturbance

source and receiver and when we have a varying electrical field between 2 conductors. One is the disturbance source and the second one is the receiver. The electrical field is generated by the voltage generated from the disturbance.

• Radiated coupling. The distance is more than several wavelengths. The source emits an

electromagnetic wave received by the device. In this case, everything could be considered as an antenna (bad antenna but enough good for receiving the disturbance)

It’s possible to have continuous interference or transient interference. The interference can be created by another device or by the device itself (I.e. if the power supply is not well decoupled, a coupling of transient signals created by this device propagates through the power to other components). Transient interferences could be created by switching phenomena because it creates spikes that emit a spectrum of frequencies to the system which may interfere with them. EMC design is a robust design where the electromagnetic interferences are minimized by respecting different rules such as:


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• Distance between cables and wires • Cables and wires close to the conductive and earthed, side wall or area • Separation of digital signals from analog signals • Separation of high voltage from low voltage cables • Decoupled cables • Removing all unwanted antennas • Clean grounds with low impedance by means braided thick and short earth connection • Respecting the return path of signals (earth system)

2.1 EMC in Switchgears

The switchgear itself is the main source for the disturbance you can have in a substation. It is generated by every operation due to discharges in the isolated compartments. In an AIS panel the discharge problem is smaller because of an early ionisation of the discharge in the air while the distance between disconnector and busbar is quite far. The discharge happens at the peak of the 50Hz sinusoidal signal. The discharges in air are of lower power with relative slow rise and fall time, which generate a frequency spectrum in its lower end (< 2 MHz).

While in GIS this phenomena is more severe because the insulation is done with insulation Gas SF6 and the ionisation process starts only when the contacts are very close to each other. In this moment the discharged energy is much higher with very fast rise and fall time in the order of 2 ns. L_C networks will be aggregated and start to oscillate on frequencies of 20 - 80MHz, depending on the L and C values. Especially this kind of disturbance is getting distributed all over the cabling inside the switchgear and can generate defects with an immediate effect or a partial defect which may later or never occur.

The picture above shows the discharge process in switchgear.

Since the connected cable shield of the outgoing power cable, the busbar, and the disconnector to the busbar can be seen as a circuit of capacitance and inductance with a certain resonance frequency. If the arc produces a frequency spectrum in the range of the resonance frequency of that LC Cirquit, the phenomena is getting amplified in voltage, as well extended in its duration.

Bus-Bar Disconnector

50 Hz

20 … 80 MHz <10 cycle>50 kW in GIS

Bus-Bar Disconnector

50 Hz

20 … 80 MHz <10 cycle>50 kW in GIS


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Without a correct wiring, good shielding and earth concept, - problems will occur in the function of the panel when a digital relay has to support it.

The description above shows that in a panel not only the 50 Hz frequencies are present. When high frequencies occur, i.e. due to discharges, it is important that braided flat cable is used to overcome the skin effect. This is important when we look at earth points and earth systems but also for cable shield and its connection to earth.

2.2 Earth Points / Earth System From HF point of view always and area to area connection is required because of the skin effect. Also the earth connection has to be made with braided thick cable and as short as possible.

Important to note: On all screwed connections spring washers or Lock washers have to be used!

Here are some pictures how earth points as they can be found sometimes today:

Busbar = Inductor

Discon-nector~70 pF

Cable - Shield> 10 nF

Radio Frequency Resonant Circuit (20…80MHz)

oscillatory waveafter each arc

Busbar = Inductor

Discon-nector~70 pF

Cable - Shield> 10 nF

Radio Frequency Resonant Circuit (20…80MHz)

oscillatory waveafter each arc


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Coloured earth point (100% isolated); No colour applied here! Also press nuts only into blank metal!

Thin earth cable; should be short and thick. Earth bold directly close to HMI

Door is earthed via long thin cable; Use short braided cable band from door earth point to compartment earthpoint


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The picture below shows a earth grid system as it is required by the IEC 61936 or DEP 33.62.10.33 standard which is generally applicable to all installations/applications on site.

Coating has to be removed! Area connection has to be achieved


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2.3 Cable Shields and Wiring In a switchgear different type of signals are used. These are CT/VT signals, I/O signals, auxiliary power supply lines, Communication signals. From EMC standpoint, all need to be handled different and need to be respected all over in and outside the panel wiring.

If i.e. a CT signal at nominal current is routed in parallel with the mains (power cable) at 50Hz, then this generates on the CT signal a significant disturbance by interference. The two signals are too different from each other so that any transition on the mains will generate interferences on the CT signal, in case the shielding is not or wrong/bad connected. This may result in a misinterpretation of the CT signal, in some cases even the relay input channel gets destroyed.

That example is valid for all different signals in the switchgear. It is therefore important to separate the different kind of cable from each other. Good results can be achieved when I/O Cables and auxiliary power is separated from analog input signals and also electrical communication cables are routed alternatively.

Shielded cables are to be used for CT cabling and communication cables. Also outside the panel, by means onsite installation!

Communication cables connected to SCADA systems outside of the switchgear need to be shielded as well. The shield should be connected only on one side, the SCADA side. The reason is because any level difference between the Switchgear and SCADA would be handled over the shield which further introduces capacitive coupling to the signal wires.


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3 Standard switchgear combinations The panels and used technology inside have different sensitivity in respect to EMC. It shows that AIS and CTs are least sensitive but also having this combination it can be heavily disturbed by any interference.

3.1 AIS with CT Best case combination from disturbance production standpoint, because the discharges are of lower power with a spectrum at the lower frequency band. In this constellation all electronic should withstand disturbances when it is correct wired and respecting EMC. Failures in the earth concept can be tolerated but have to be excluded in any case. Experience has been show that when cable lengths, routing and shielding are not respected problems may happen. Since the electronic is fulfilling the standard EMC requirements no problem should occur due to EMC.

3.2 GIS with CT That combination may already lead to EMC problems with the electronic components because the GIS produce disturbances which are of high power and severe. It might be that a relay has some misbehavior when the earthing is done weak from HF point of view. The CT acts as filter towards the analog inputs of the relay. Further all signals have rather high amplitude and are more robust. Anyway always cable lengths, routing and shielding have to be respected to avoid problems and being EMC compatible.

INom is 1 Ampere; BIO signals are at Auxiliary Voltage (60 … 250V);

3.3 AIS with Sensors A further more sensitive combination due to the fact that the sensor signal is much smaller as the other signaling in switchgears. Any operation may have interference with the sensor signal and can lead to a faulty behavior. With sensors it is important to have the outer shield connected on both sides of the cable well to earth. Further details see next paragraph “GIS with Sensors”.

3.4 GIS with Sensors From EMC standpoint it is the worst case scenario. Harsh disturbance is generated by the GIS discharge phenomena plus having Rogowski coils installed. The sensor itself acts as 1. Order high pass filter by means high frequency signals can pass unfiltered. Further the nominal current is transferred as a voltage signal with 150mV amplitude. Transients even from I/O signals are factor 1000 higher than the nominal current signal! If the wiring and earthing is done in the wrong way, faulty behavior will occur. In addition the discharges from operation can easily lead to spurious exceptions/trips because the disturbance is also by factors higher than the signal itself when the wiring is done wrong way.

Without good earth concept and also incorrect wiring, misbehavior will occur. Further the disturbances generated in one of the switchgears can lead to spurious trips in any next switchgear, due to the fact that the disturbance is following the lowest impedance path.

When sensors are applied in any applications, it has to be done with REF542plus devices. The bad reputation of the REF542plus is often based on the usage for this combination. As the reviews have shown, correct wiring and earth connection is often neglected and resulting in a failing of relays.


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The pictures below show two examples on how the outer shield can be connected to the chassis of the switchgear. The second picture shows also how intermediate earthing of the shields can be done.

4 IED installation The IED has to be mounted at the standard locations in our panels. It is important that the device gets and area connection to earth via the mechanical mounting support or via a braided flat cable short to the chassis of the switchgear. The cables need to be separated routed by means Sensor/CT/VT cables separate from I/O and power supply cables. Communication cables should be handled also separate. The picture below shows how a relay gets installed in a ZX. It is visible that the device is area connected to the chassis through a metal support. When the support is getting mounted to a mounting (rails) frame it need to be checked that this frame is also area connected to the main chassis. This can be done by using braided flat cable to the chassis. What needs also to be observed is that the cover is getting earth connected to the body of the housing with a short braided cable link. That’s important in case of REF542plus because the cover has no area connection to the body of the housing.


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Separate wiring example. Please keep separation also with the cable ducts.

4.1 Installation requirements for protections relays In general, the rules for design and installation in accordance with IEC 61000-5-1 and IEC 61000-5-2 shall be followed in order to achieve an Industrial level EM environment (as described in IEC 61000-2-5 – see also IEC 61000-6-2) inside low voltage compartments here protective relays or other instruments are located. More specifically, the following installation requirements apply: Protection relays shall be installed in metallic, shielded cabinets or cubicles. The equipment enclosure shall be bonded to the conductive surface of the cabinet or cubicle. In case of separate relays and door displays/ terminals,

Cover earthed to body with short braided cable

Area to area connection to chassis resp. earth.


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wiring between these elements shall be shielded. All cables to equipment inside HV switchgear cubicles shall be shielded. The shield shall have low transfer impedance properties and be bonded at both ends at the HV cubicle and the secondary cubicle or cabinet, using short, low impedance connections, such as cable clamps or cable glands. Differential mode circuits shall be kept compact by installing lead wires and their return wires in the same cable loom or cable trunk. All solenoids of relays, contactors or circuit breakers shall have adequate de-coupling devices to suppress high frequency interference to electronic protection relays. The cable armouring and conductive sheathing of HV cables shall be continued to and be terminated at the HV cubicle in accordance with the vendors installation instructions. Additional bonding to the substation earth bar/ring may be applied to reduce the impedance for power frequency return currents in the event of an earth fault. The armouring and or shielding of external secondary cables shall be continued and terminated at the secondary cubicles or cabinets, using low impedance connections such as cable clamps or cable glands. A condensed version of the standard IEC 61005 – 6-5 can be found in the appendix chapter.

4.2 Earth screw Power Supply REF542plus It needs to be verified that the earth screw of the power supply is applied in case of REF542plus. For the isolation tests, this screw has to be removed and afterwards reinstalled. In some cases this gets forgotten, which leads EMC problems because the EMC input filter of the power supply is then disabled.

4.3 Recommendation for digital input delay setting of an IED (REF542plus) At digital inputs the filter time eliminates debouncing and short disturbances on a digital input. A voltage greater than 38V and a current of 1,8mA are sufficient to switch the binary inputs from 0 to 1 (low to high status) or reverse; even if the voltage is applied for only 4msec (hardware filter time of the IED).

Earth screw has to be mounted!

Earth cable not suitable! See example above.


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The filter time can be set for each digital input of the IED feeder terminal individually. A filter time of minimum 20msec. must be set. Alternative interposing relays may be installed to critical binary inputs, like trip circuits if an extended cable length is expected (> 200Meter). Below that cable length, minimum shielded cables have to be used.

5 Cable routing In order to reduce interference coupling, as far as possible run the cables close to metal parts which are connected to the reference potential (mounting plates, switch cabinet etc.) Live cables should also be run as close as possible to the reference potential (to reduce inductively coupled interference). In order to improve electromagnetic compatibility, preference should be given to cable ducts, cable troughs and installation tubes which are made of metal rather than plastic parts. Cables and wires off different classes’ e.g. binary and analogue cables must be routed with a different of min. 20cm and should be crossed in an angel of 90°.

In the case of unshielded signal cables, (forward and return lines) use twisted-pair lines, in order to minimize the area between the wires (to avoid magnetic coupling). Also loops have to be avoided.


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5.1 Classification of signals according to level of interference

5.2 Max. Length of control cables connected to binary inputs In case of armored multi core cables the maximum lengths is 50m. If the cable type is well chosen (screened, twisted) the maximum length is 200m. For control wires and specially for “tripping” wires with a length > 200m interposing relays must be considered.

• <50m length, armored cable • 50 - 200m length, shielded / twisted “multi core” cable (see Table 2 of

DEP 32.37.20.10-GEN) • >200m length, in addition to the shielded / twisted “multi core” cable interposing relays or

a fiber optic communication should be considered.

5.3 Minimisation of differential mode (DM) loops in LV compartments To avoid DM loops the 110V DC plus and minus are switched in double pole MCCB’s and routed together to individual devices as far as possible. For external Signals which are routed via control cables between the different locations the lead and return wire must be routed in the same cable.

5.4 Wiring of external Ring CT’s and VT’s


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Cabling or wiring to or from external current or voltage transformers to the low voltage compartment, e.g. underneath the switchboard (“ct box”) must be screened/shielded and separated from the high voltage cables, in any case. See requirement DEP 33.62.10.33.

5.5 Treatment of spare wires of the Relay Spare cores inside the LV compartments specially the wires going to an IED are generally earthed at booths sides. This also applies for spare wires from external control cables and interpanel wiring.

5.6 Maximum length of excess wiring inside switchboards Basically all cables/wires specially coming from outside must be as short as possible. It is recommended to have the excess wire length not longer than 25cm! Special attention has to be given to avoid unnecessary wire loops by winding up the excess cable. Where excess cable length can note be avoided e.g. combined sensor cable, than this shall not be stored in high voltage compartments, furthermore this excess cable length should be pulled inside the low voltage compartment.

5.7 Requirements for LV signal cables going to the REF relays The armouring and or shield of the external control cables must be connected as short as possible to the earth bar in the low voltage compartment. (as per DEP) All cable shields and or armouring must be earthed at both sides of the cable.

5.8 Cable entry for HV single and 3-core cables, LV cables, CTs cables. High voltage termination should be strictly in accordance to document T-12.672.334 (which is available on request).

We highly recommend that the terminations of the HV Cable will be done by certified personnel, preferably by cable/plug supplier site personnel.


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Please refer to the attached document ABB 1VB 1031599 in appendix section LV cables should always be shielded; including cable/wires going to or from external ring CTs. LV multi core cable shield bonding must be as short as possible.

6 EMC-compliant earthing of the switchgear Electromagnetic compatibility (EMC) is to be planned from quantitative points of view. The interface requirements regarding emissions and immunity are to be stipulated for delimited areas (EMC zones). In the best possible case, these requirements can be met directly, i.e. with no additional action. If, however, the requirement are not fulfilled, additional actions are necessary, and is in principle to be applied in the order of the interference source, coupling path and interference sink. It is useful to assess the hierarchical elements of a system, such as the complete plant equipment, room, cubicle assembly, rack assembly, circuit board, circuit section and component, with respect to their electromagnetic environments on the various levels. The design of the earthing system for the switchgear is of decisive importance for the EMC of the secondary equipment in the switchgear installation. Information on this can be found in IEC 61936 standard, section 9.5. According to IEC 60694 (in future IEC 62271-1), the secondary equipment in the switchgear system must satisfy the requirements of sections 2.1 and 6.9. It is then ensured that interference which is permissible under the terms of the standard does not impair the immunity to noise of the secondary equipment (see IEC 60694, Annex H and Annex J of the future standard IEC 62271-1). The measures are to be implemented in addition to the earthing system described in section 4.1. Limitation of the interference level within the switchgear system is supported by suitable measures as listed below. • Separate routing of power, signal and control cables. • Suitable screening and earthing of the equipment. • Potential isolation: Galvanic isolation of the signal circuits at the system boundary. • Equipotent bonding: For low-impedance connection of system or circuit sections between which the potential difference should be as low as possible

6.1 Design of earthing systems with regard to touch voltage and thermal stress The earthing system for the station building and the earthing system for the switchgear are to be designed in accordance with IEC 61936. The switchgear system is to be fitted with a continuous copper earthing bar with a cross-section of 400 mm2 (ECuF30, 40 mm x 10 mm). The connection of this earthing bar to the station earthing system is to be effected in accordance with the above standards.


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The earthing system described in this section does not represent EMC-compliant earthing of the switchgear. EMC-compliant earthing is achieved by additional measures which are explained in the following section.

6.2 Bonding of earth bars in LV compartments All LV compartments have to have a “to earth connected” earth bar, via a low impedance earth strap at either end of the bar.

6.3 Bonding/ earthing of main switchgear earth bar (max. distance between bonds) Every Panel should be earthed/bonded to the main earth grid (approx. 5mx5m) Please refer to the appendix of this document

6.4 Recommendations on configuration of the switchgear earthing It is recommend that the switchgear to be earthed as shown in figures 4.1 and 4.2 A ring consisting of 80 mm x 5 mm copper strip is to be located beneath the switchgear and connected at several points with a maximum spacing of 5 m to the earthing system of the building. The foundation frame, the main earthing bar in the panels and the earthing bar in the low voltage compartments are to be connected at multiple points to the ring located beneath the switchgear. Details on the use of materials and the number of connections can be found in figure 4.1. When planning the switchgear earthing, please observe the notes in sections 4.1 and 4.2.


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Fig. 4.1: Earthing recommendation, shown schematically as a sectional elevation of the lower part of a panel including the concrete floor Fig. 4.2: Earthing recommendation, plan view (section A-A of figure 4.1) Cable compartment

Figure 4.1 section A-A

Figure 4.2


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6.5 Recommendation for substation earth grid construction The DEP describes this very detailed. We do not have further recommendations. The EPC at site must follow the DEP. Approximately a 5m by 5m earth-grid is recommended.

7 Appendix

7.1 Golden Rules to avoid EMC disturbance 1. Ensure high-frequency (HF) and low-frequency (LF) EQUIPOTENTIAL BONDING of exposed conductive parts :

- locally (installation, machine, etc.) - at site level

2. Never route sensitive class* (1-2) signals and interfering class* (3-4) signals in the same cable or bunch of conductors.

3. Minimise the length of parallel running cables carrying signals of different classes: sensitive (class1-2) and interfering (class 3-4).


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4. Maximise the distance between cables carrying signals of different classes*, especially sensitive signals (1-2) and interfering signals (3-4) - this is very effective and relatively inexpensive. 5. Minimise the surface area of earth loops 6. The OUTGOING conductor must always be routed as close as possible to the RETURN conductor. 7. Using shielded cables makes it possible to co-locate cables carrying signals of different classes in a single cable trough. 8. Shielding connected at both ends

• Very effective against external disturbances (high frequency (HF), etc.), • Very effective even at resonance frequency of cable, • No potential difference between cable and frame connection, • Makes it possible to co-locate cables carrying signals of different classes (assuming satisfactory connection (360°) and equipotential bonding of exposed conductive parts (interconnection, etc.), • Very high reducing effect (high frequency (HF)) - is 300, • In the case of extremely high-frequency (HF) signals, may induce leakage currents to earth for long cables > 50-100 m.

9. Any conductor in a cable and which is spare or not used must always be earthed (chassis, cable trough, cabinet, etc.) at both ends. 10. Make sure conductors or cables carrying signals of different classes, especially sensitive signals (1-2) and interfering signals (3-4) cross each other at right angles. 11. Earth fault protection function should not be calculated by an multi function device like the REF542 plus. The earth fault should be measured via a cable ct ore a ct on the secondary side. 12. All connection to earth must have a minimum average of 16mm²

7.2 Immunity requirements for protection relays Electronic protection relays installed in a separate control room shall comply with the immunity requirements as per IEC 61000-6-5, area G (equipment installed in power stations and MV substations). Electronic protection relays installed in a HV switchgear room, back-to-back with switchgear cubicles, shall comply with the immunity requirements as per IEC 61000-6-5, area H (equipment installed in HV substations), regardless the level of the high voltage. In addition to the above, electronic protection relays in areas G and H , as defined in IEC 61000-6-5, shall comply with the oscillatory wave immunity requirements as per IEC 60694 and basic standard IEC 61000-4-12, with test frequencies of 10 MHz and 50 MHz and test levels as specified in the table below.


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Additional immunity requirements for protection relays in areas G and H , as defined in IEC 61000-6-5 For all ports connected to equipment inside HV switchgear cubicles, such as VT, CT, pressure transmitters, temperature transmitters and position indicators, the common mode (CM) test level of 2.5 kV is also to be applied differential mode (DM), as shown in the Table.

7.3 Performance criteria The protection relay shall withstand each of the immunity tests specified in 7.2 without damage or malfunction. Where the primary protection and measurement functions of protection relays are concerned, no degradation or temporary loss of function is allowed (performance criterion 1 or A). Further reference regarding performance criteria for various functions of secondary equipment is given in IEC 61000-6-5, the content of which shall be complied with.


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7.4 Single core cable bonding


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7.5 Cable Bonding different types

Cable bonding for GIS applications. Partly applicable also for AIS.


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7.6 Switchgear Earthing


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REVISION Rev. ind.

Page (P) Chapt.(C)

Description Date Dept./Init.

New document 2008-03-17, B.Deck CHSEC

0.1 all Review 2008-03-19 W.Ebbinghaus;S. Wehrmann DECMS

1.0 Release 2008-03-20 B.Deck CHSEC

application guidelines secondary wiring ais - gis

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