g7c-1102-00

THE DOW CHEMICAL COMPANY DESIGN AID ELECTRICAL G7C-1102-00 GLOBAL 07-OCT-2008

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DOW RESTRICTED - For internal use only

ALARM AND STATUS SIGNAL GUIDELINES FOR PLANT ELECTRICAL DISTRIBUTION SYSTEMS

1.0 SCOPE

This practice is intended to provide guidance on the alarm and status signals that should be monitored on a given electrical system by the combination of a common alarm panel (or panels) and the Mod 5. The electrical systems considered for this practice include the most common variations of the main-tie-main, double ended (preferred alternate) feed, and single ended feed distribution schemes. Guidelines for general alarm panel layout and operation are also given. For applications where process control systems other than the Mod 5 are used, the specific I/O descriptions and requirements still apply.

2.0 GENERAL INFORMATION

Alarms and status signals play an extremely important role in the safe and effective operation of plant electrical distribution systems. Past design history suggests these signals have been monitored by the Mod 5, an alarm panel, or some combination of both. Additionally, the exact electrical equipment alarm and status inputs that have been monitored have varied greatly by plant and site location globally.

The alarm and status monitoring guidelines given in this practice are influenced by two basic assumptions. First, Mod 5 inputs are expensive and should only be used for critical alarms and status inputs required to make equipment control decisions. Second, the appropriate response to a given electrical alarm or status signal will require the aid of a qualified electrical technician.

Based on these assumptions this practice details guidelines that minimize the input signals required to the Mod 5. At the same time, the practice will make recommendations for a common alarm panel that monitors alarm and status signals required for the safe, effective operation of electrical distribution equipment.

3.0 MOD 5 ALARM AND STATUS SIGNAL INPUTS

3.1 CONTROLLED MOTOR RESTART DIGITAL INPUTS (DIs)

The Mod 5 will require information about main breaker and/or tie (coupler) breaker positions as well as bus voltage information to properly initiate motor restart signals. The requirements and philosophy behind Mod 5 Controlled Motor Restarts are detailed in EMETL practices G7B-0705-01 and G7B-0705-02. Mod 5 restart DI requirements are listed below for the three most common distribution system types. For each system type it is assumed the appropriate breakers are tripped and locked out in the event of a bus fault.

3.1.1 MAIN-TIE-MAIN SYSTEMS

A total of six (6) DIs will be required for the controlled restart of a main-tie-main system. Each required DI is explained below.

3.1.1.1 Incoming Main Circuit Breaker 1 operational state (Open/Closed) 3.1.1.2 Incoming Main Circuit Breaker 2 operational state (Open/Closed) 3.1.1.3 Tie (Coupler) Circuit Breaker operational state (Open/Closed) 3.1.1.4 Bus 1 Voltage (Yes/No) 3.1.1.5 Bus 2 Voltage (Yes/No) 3.1.1.6 Manual/Auto Selector Switch position (Manual/Auto)


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3.1.2 DOUBLE ENDED (PREFERRED ALTERNATE) FEED SYSTEMS

3.1.2.1 Incoming Main Circuit Breaker 1 operational state (Open/Closed) 3.1.2.2 Incoming Main Circuit Breaker 2 operational state (Open/Closed) 3.1.2.3 Bus Voltage (Yes/No) 3.1.2.4 Manual/Auto Selector Switch position (Manual/Auto)

3.1.3 SINGLE ENDED FEED SYSTEMS

3.1.3.1 Incoming Main Circuit Breaker operation state (Open/Closed) 3.1.3.2 Bus Voltage (Yes/No)

3.2 ALARM AND STATUS DIs

Each alarm panel shall have two (2) DI signals monitored by the Mod 5.

3.2.1 One (1) DI signal shall be a common alarm that can be triggered by any alarm condition wired to the panel. The common alarm may be acknowledged at the Mod 5 but will remain active until the alarm condition has been reset at the alarm panel.

3.2.2 One (1) DI shall be an unacknowledged alarm condition. If the common alarm is

not acknowledged at the alarm panel within fifteen minutes, the unacknowledged alarm condition shall be triggered. The unacknowledged alarm shall cycle (reset and trigger) every fifteen minutes until the common alarm has been acknowledged at the panel.

3.3 CRITICAL RELAY SELF DIAGNOSTIC DI SIGNALS

3.3.1 For electronic protective relays, and PLC s, the device failure alarm contacts shall

be wired directly to the Mod 5 and to the annunciator panel.(See paragraph 4.13). The relay failure alarms associated with transformer, bus, and feeder protection may be grouped, and wired to the Mod 5 as a single DI. However, these relays should be monitored individually at the alarm panel.

3.3.2 iAn electronic protective relay and PLC failure contact shall also be provided for use

with a phone dialer. At some sites, phone dialers are used to page or fax on-call personnel responsible for responding to protective relay failure alarms.

3.4 iiMISC ALARMS

3.4.1 iii Stage 1 and Stage 2 common UPS Trouble Alarms shall be configured for all UPS systems. Stage 1 alarm configuration may include the following points: Low/High DC, Inverter Trouble/Failure, Static Switch Failure. Loss of Primary AC, Loss of Bypass source, etc. The Stage 2 alarm shall include Batteries Discharging. Note: This alarm may be detected by loss of all incoming AC power sources.

3.4.2 A common Automatic Transfer Switch Trouble alarm should be configured for all low voltage automatic transfer switches. Alarm configuration may include the following points: Loss of normal source, loss of secondary source, transfer logic failure, etc.


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3.4.3 Separate battery rooms should be equipped with a common Battery Room trouble alarm. Alarm configuration should include monitoring of high temperature and loss of ventilation.

3.4.4 Loss of capacitor trip device (CTD) power from medium voltage contactors should be configured to alarm on failure to a manned location. Alarms may be paralleled to a common loss of capacitor trip device alarm on a common MCC bus system.

4.0 ALARM PANEL LAYOUT, OPERATION AND SIGNALS

4.1 All required alarms associated with a given plant distribution system (and not taken directly to the Mod 5) shall be located in a panel or panels within the electrical switchgear building.

4.2 For European sites only, the monitored alarms shall be contained in a single, central panel

containing three alarm groups. Group one shall include alarms from system side 1 and associated tie breakers (Couplers) at all plant voltage levels. Group two shall include alarms from system side 2 at all plant voltage levels. Group 3 shall include miscellaneous alarms as listed below at all plant voltage levels. Refer to the optional alarms listed in sections 4.14 - 4.16.

4.3 For all other locations globally, system alarm groups may be located together in a single

central alarm panel, or each group may be located in the corresponding system remote control panel. The alarms monitored shall be grouped by system voltage level and not system side.

4.4 Each alarm panel shall be equipped with Acknowledge, Test and Reset buttons on the

front of the panel.

4.5 ivUpon receipt of an alarm signal, the alarm panel window corresponding to the incoming fault condition shall light up and flash. A common alarm DI shall be generated by the panel and sent to the Mod 5.

4.6 Once the alarm is acknowledged by pressing the panel acknowledge button, the audible

alarm shall be silenced, and the alarm window light shall change from flashing to steady. The alarm window shall then remain lit until the alarm is cleared. The Mod 5 common alarm DI shall also remain in the alarm present state until the condition has been cleared.

4.7 Upon receiving an additional fault or alarm condition the above sequence shall be repeated.

4.8 If an alarm condition is not acknowledged within 15 minutes, an additional unacknowledged

alarm shall be generated by the panel and sent to the Mod 5. The unacknowledged alarm should cycle (reset and trip) every 15 minutes until the given alarm condition is acknowledged. Once triggered, this alarm should remain active for five minutes to allow the operator time to acknowledge it at the Mod 5.

4.9 The alarm panel shall be capable of receiving multiple alarms on the same window for

subsequent conditions. If a subsequent condition occurs for an acknowledged alarm that has not been cleared, the alarm window should once again start flashing and the horn shall sound.

4.10 The Test button shall initiate all alarm windows at once to check for functionality and

proper operation. In test mode, all alarm window lights shall flash and the horn shall sound as for an actual alarm.


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4.11 The Reset button shall be used to reset the panel. Pushing the reset button shall momentarily clear and reset all panel alarms. If all alarm conditions are truly cleared, the panel windows will be reset and the Mod 5 alarms will be cleared. However, if an alarm condition still exists, the appropriate alarm window shall be re-activated.

4.12 System Electronic Relays and/or PLC monitoring systems with status/alarm display

capability shall send a common alarm signal to the alarm panel, indicating which device needs to be interrogated. If any of the listed alarms below are already contained in an electronic relay or PLC system, they are not required to also be wired to the alarm panel.

4.13 System Electronic Relays and PLC s typically have self diagnostics capabilities. If the

electronics fail a relay or PLC device failure alarm is generated. In addition to the annunciator electronic relay common alarm, device failure contacts shall be wired directly to the Mod 5 based on the critical nature of the device.

4.14 MAIN-TIE-MAIN SYSTEMS

As a minimum, the following alarms should be monitored for each plant main-tie-main system regardless of voltage level. Any explanation or comments associated with the alarms listed are located in section 5 of this specification. Where applicable, section 5 paragraphs are cross referenced in the list below.

4.14.1 Incoming Main Circuit Breaker 1 Trip (Fault or Undervoltage Transfer) See 5.1 4.14.2 Incoming Main Circuit Breaker 1, Trip Coil Supervision See 5.2 4.14.3 vBus 1 Electronic Relay/Relays Common Alarm See 5.3 4.14.4 Incoming Main Circuit Breaker 2 Trip (Fault or Undervoltage Transfer) See 5.1 4.14.5 Incoming Main Circuit Breaker 2, Trip Coil Supervision See 5.2 4.14.6 Bus 2 Electronic Relay/Relays Common Alarm See 5.4 4.14.7 Tie (Coupler) Circuit Breaker Trip (Due to Fault) See 5.1 4.14.8 Tie (Coupler) Circuit Breaker Trip Coil Supervision See 5.2 4.14.9 Tie (Coupler) Circuit Breaker Close Coil Supervision See 5.5 4.14.10 Auto/Manual Switch, Switch in Manual Alarm See 5.6 4.14.11 Auto-Transfer System Common Alarm See 5.7 4.14.12 Each Bus 1/2 Feeder Breaker, Fault Trip 4.14.13 Transformer 1, Common Alarm Oil Type Only See 5.8 4.14.14 Transformer 1, High Temperature Alarm Dry Type Only See 5.9 4.14.15 System 1 Ground Fault Alarm 4.14.16 System 1 Ground Fault Monitor Trouble Alarm 4.14.17 Transformer 2, Common Alarm Oil Type Only See 5.8 4.14.18 Transformer 2, High Temperature Alarm Dry Type Only See 5.9 4.14.19 System 2 Ground Fault Alarm 4.14.20 System 2 Ground Fault Monitor Trouble Alarm 4.14.21 Battery Charger Trouble Alarm

The following alarms may be optionally added to the minimum alarms list for each plant main-tie-main system regardless of voltage level.

4.14.22 Feeder Breaker Trip Coil Supervision for systems above 690 Volt Only, 4.14.23 Bus 1, High Amps 4.14.24 Bus 2, High Amps 4.14.25 Instrument Power Panel Failure (Europe Only) 4.14.26 Lighting Power Panel Failure (Europe Only)

4.15 DOUBLE ENDED (PREFERRED/ALTERNATE) FEED SYSTEMS


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As a minimum, the following alarms should be monitored for each plant Double Ended system regardless of voltage level. Any explanation or comments associated with the alarms listed are located in section 5 of this specification. Where applicable, section 5 paragraphs are cross referenced in the list below.

4.15.1 Incoming Main Circuit Breaker 1 Trip (Fault or Undervoltage Transfer) See 5.1 4.15.2 Incoming Main Circuit Breaker 1, Trip Coil Supervision See 5.2 4.15.3 viBus 1 Electronic Relay/Relays Common Alarm See 5.3 4.15.4 Incoming Main Circuit Breaker 2 Trip, Fault or Undervoltage Transfer See 5.1 4.15.5 Incoming Main Circuit Breaker 2, Trip Coil Supervision See 5.2 4.15.6 Bus 2 Electronic Relay/Relays Common Alarm See 5.4 4.15.7 Auto/Manual Switch, Switch in Manual Alarm See 5.6 4.15.8 Auto-Transfer System Common Alarm Europe Only See 5.7 4.15.9 Each Bus 1/2 Feeder Breaker, Fault Trip 4.15.10 Transformer 1, Common Alarm Oil Type Only See 5.8 4.15.11 Transformer 1, High Temp Alarm Dry Type Only See 5.9 4.15.12 System 1 Ground Fault Alarm 4.15.13 System 1 Ground Fault Monitor Trouble Alarm 4.15.14 Transformer 2, Common Alarm Oil Type Only See 5.8 4.15.15 Transformer 2, High Temperature Alarm Dry Type Only See 5.9 4.15.16 System 2 Ground Fault Alarm 4.15.17 System 2 Ground Fault Monitor Trouble Alarm 4.15.18 Battery Charger Trouble Alarm

The following alarms may be optionally added to minimum alarms list for each plant double ended system regardless of voltage level.

4.15.19 Feeder Breaker Trip Coil Supervision for Systems Above 690 Volt Only 4.15.20 Bus, High Amps 4.15.21 Instrument Power Panel Failure (Europe Only) 4.15.22 Lighting Power Panel Failure (Europe Only)

4.16 SINGLE ENDED FEED SYSTEMS

As a minimum, the following alarms should be monitored for each plant Single Ended system regardless of voltage level. Any explanation or comments associated with the alarms listed are located in section 5 of this specification. Where applicable, section 5 paragraphs are cross referenced in the list below.

4.16.1 Incoming Main Circuit Breaker Trip(Due to Fault) See 5.1 4.16.2 Incoming Main Circuit Breaker, Trip Coil Supervision...>690Volt Only See 5.10 4.16.3 viiBus Electronic Relay/Relays Common Alarm See 5.3 4.16.4 Each Bus 1/2 Feeder Breaker, Fault Trip 4.16.5 Transformer, Common Alarm Oil Type Only See 5.8 4.16.6 Transformer, High Temperature Alarm Dry Type Only See 5.9 4.16.7 System Ground Fault Alarm 4.16.8 System Ground Fault Monitor Trouble Alarm 4.16.9 Battery Charger Trouble Alarm

The following alarms may be optionally added to minimum alarms list for each plant single ended system regardless of voltage level.

4.16.10 Feeder Breaker Trip Coil Supervision(For Systems Greater than 690Volt Only) 4.16.11 Bus, High Amps 4.16.12 Instrument Power Panel Failure (Europe Only)


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4.16.13 Lighting Power Panel Failure (Europe Only) 5.0 ALARM SIGNAL NOTES

5.1 An Incoming main circuit breaker trip alarm should only be the result of a fault condition or an undervoltage transfer. The equipment should be designed so that a manual trip from the breaker or remote control panel does NOT initiate this alarm. This can be accomplished by the use of slip contacts on the manual control switch (52CS) or by a blocking diode in the trip circuit.

5.2 The trip coil supervision alarm shall also double as a loss of control voltage alarm for main

incoming breakers. In general, trip circuit monitors inherently alarm on loss of dc control voltage. A technician can quickly establish if the alarm is a coil failure or control voltage failure by observation of the equipment lights.

5.3 viiiThe Bus 1 electronic relay common alarm monitors the state of alarm contacts for all

electronic relays at a given voltage level on system A. For European/IEC or other non-partial differential schemes, this alarm should also monitor alarm contacts of electronic relays associated with the tie breaker (coupler). In addition to abnormal system conditions, the electronic relay common alarm should also trigger for relay failures.

5.4 ixThe Bus 2 electronic relay common alarm monitors the state of alarm contacts for all

electronic relays at a given voltage level on system B. In addition to abnormal system conditions, the electronic relay common alarm should also trigger for relay failures.

5.5 In order to ensure the successful operation of a tie breaker (coupler), the close coil must be

properly monitored. Similar to trip coil supervision, a close coil circuit can also be configured to alarm for loss of control voltage.

5.6 Although the Auto/Manual selector switch position is sent to the Mod 5 for the purposes of a

controlled auto-restart, it is also desirable to monitor the condition via the local alarm panel. This is due to the importance of not leaving the Auto/Manual switch in the Manual mode.

5.7 The Automatic Transfer System (ATS) is a PLC transfer system. Locations outside of Europe

typically have hard wired transfers and will not have an ATS, PLC common alarm. In addition to required abnormal system conditions, this alarm shall also initiate in the event of a PLC failure.

5.8 The common alarm associated with Oil Type Transformers includes oil temperature, oil level,

sudden pressure or Bucholz devices, pressure relief and nitrogen pad vacuum/pressure where applicable.

5.9 For large dry type transformers, only the winding temperature is typically monitored.

5.10 Feeder breakers applied at voltages of 690 and below are generally outfitted with static trip

units. This is also true of main breakers applied on single ended systems. Typically, it is not possible to monitor the trip coil health associated with a static trip unit. Additionally, the static trip units do not require control voltage to trip for fault conditions. As a result, Trip Coil Supervision is not required on feeder breakers with static trip devices. However, a Trip Coil Supervision alarm may be considered for feeder breakers without static trips depending on the protective settings of the upstream main breaker. For single ended system, the main breaker trip coil should always be monitored for units without static trips.


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5.11 xAlarms should be configured to monitor the trip coils of critical lockout relays (e.g. bus and partial differential relays, transformer differential relays, etc. when the lockout is supplied from a dedicated source. A common lockout trouble alarm may be configured for a single bus application.

i 11-JAN-01,MOC2000.129, BY:John Lechmann, Supercedes Issue Date 04-Aug-2000 revised paragraph 3.3.2 to read protective relay failure alarms. ii 24-OCT-2001,MOC2001.111,By:P. Gabba, Supercedes Issue Date:11-JAN-2001, Added text related to Miscellaneous alarms paragraph 3.4. iii 07-OCT-2008; MOC 2008_06631; By: Paul Gabba; Supersedes Issue Date 25-OCT-2001. Paragraph 3.4.1 divided UPS alams into two different Stages. iv 11-JAN-01,MOC2000.129, BY:John Lechmann, Supercedes Issue Date 04-Aug-2000 Paragraph 4.5 removed need for audible alarm sound v 11-JAN-01,MOC2000.129, BY:Ted Knight, Supercedes Issue Date 04-Aug-2000 revised paragraph 4.14.3 removed word trouble and changed BusA to Bus1 vi 11-JAN-01,MOC2000.129, BY:Ted Knight, Supercedes Issue Date 04-Aug-2000 revised paragraph 4.15.3 removed word trouble and changed BusA to Bus1 vii 11-JAN-01,MOC2000.129, BY:Ted Knight, Supercedes Issue Date 04-Aug-2000 revised paragraph 4.16.3 removed word trouble. viii 11-JAN-01,MOC2000.129, BY:Ted Knight, Supercedes Issue Date 04-Aug-2000 revised paragraph 5.3 removed word trouble and changed BusA to Bus1 ix 11-JAN-01,MOC2000.129, BY:Ted Knight, Supercedes Issue Date 04-Aug-2000 revised paragraph 5.4 removed word trouble and changed BusB to Bus2 x 24-OCT-2001,MOC2001.111,By:P. Gabba, Supercedes Issue Date:11-JAN-2001, Added text related to monitoring trip coils paragraph 5.11

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