Common use of Motor Control Centers Clause in Contracts

Motor Control Centers. This section covers the engineering, design, manufacture, installation and testing of indoor motor control centers. The motor control centers shall supply the 480 volt station auxiliary loads. The equipment shall be suitable for operation on a 480/277 volt, three-phase, 60 hertz, grounded service. Motor control centers shall conform to the requirements of UL 845, NEMA ICS1, NEMA ICS2, NEMA ICS4, and NEMA ICS6. Each Motor Control Center shall consist of one or more vertical sections and shall be designed to permit future additions, changes, or regrouping. As a minimum, one equipped spare space for a size 2 starter shall be provided for each vertical section. In addition, one spare combination starter of each size and -------------------------------------------------------------------------------- EPC - Exhibit B -------------------- TENASKA GEORGIA GENERATION PROJECT Page 93 of 132 -------------------------------------------------------------------------------- type less than size 5 shall be supplied in each Motor Control Center. The Motor Control Center assembly shall be of a nonventilating type. All enclosure vertical sections shall be mounted on continuous front and back channel iron xxxxx and bolted firmly together to form a rigid, freestanding, dead-front, completely enclosed, front line assembly. Vertical sections shall be formed of manufacturer's standard gauge sheet steel with uniform, blemish-free surfaces. Each vertical section may contain a maximum of six unit compartments. End sections shall have removable end closing plates, and provisions shall be provided for access to horizontal bus and horizontal wireways. Easily removable blank hinged doors shall cover all unused unit spaces. Bolted covers shall be furnished on the rear of the section. The vertical bus and its insulation in the rear section shall be covered with sheet metal plates suitable for mounting control and other devices. Conduit entrance space and wire entry room greater or equal to cross-sectional area of vertical wireways shall be provided at both the top and bottom of each section. Top and bottom horizontal wireways with full length continuity shall be provided. Wireways shall be isolated from the bus bars by barriers. A vertical wireway shall extend from the top horizontal wireway to the bottom horizontal wireway for the purpose of routing cables to control units. The wireway shall be isolated from all units and the bus bars to guard against accidental contact. A separate hinged door shall cover the vertical wireway for easy and safe access to wiring without disturbing control units. The vertical wireway shall be greater than a 24 square inch cross sectional area. The vertical wireway shall have one hole, two inches or larger per unit compartment, for cables from the rear of the section to unit compartments. Hole edges shall be suitably covered to safeguard against injury to cables. Each unit compartment shall have a front door, securely mounted with rugged hinges which allow the door to swing open to facilitate maintenance. Unit doors shall be fastened to the stationary structure so they may be closed to cover the unit space when the units have been temporarily removed. A panel for any required pilot devices shall be attached to the control unit, not the unit compartment door. Panels for pilot devices shall be furnished even when pilot devices are not originally specified for control units. Motor starting and feeder tap unit doors shall be interlocked mechanically with the unit disconnect device to prevent unintentional opening of the door while energized and unintentional application of power while the door is open. Means shall be provided for releasing the interlock for intentional operation while the door is open. Provision shall be made to lock the disconnect device in the OFF position with two separate padlocks. The unit disconnect operating switch shall not be mounted on the unit door. The disconnect switch shall indicate ON, OFF, and automatic trip position with the door open or closed. Means shall be provided for padlocking the unit in the partially withdrawn and disconnected positions. -------------------------------------------------------------------------------- EPC - Exhibit B -------------------- TENASKA GEORGIA GENERATION PROJECT Page 94 of 132 -------------------------------------------------------------------------------- Each plug-in unit shall be supported and guided so that unit installation is easily accomplished. Support and guidance devices shall be easily transferred from one location to another to facilitate rearrangement of the Motor Control Center. Each unit shall be isolated from the bus compartment, wireways, and adjacent unit compartments by grounded sheet metal barriers. Hand holds shall be provided on each unit to facilitate installation and removal. Wireway holes shall be grommeted. A continuous main three-conductor copper horizontal bus shall be provided over the full length of the control center. Buses shall be mounted edgewise and supported on insulated bus supports. Front removable or sliding barriers shall be provided to prevent accidental contact with the horizontal bus. Bus bars, removable top plate, and all bolted connections shall be accessible from the front of each vertical section. The main horizontal bus and vertical bus rating shall be minimum 600 amp and 300 amp rms continuous, respectively. All buses shall be braced for an rms symmetrical interrupting current consistent with the electrical system design (e.g. 25,000 or 42,000 amps). A continuous copper ground bus capable of carrying short circuit current shall be rigidly bolted to the structure across the full length of the Motor Control Center. Equipment requiring grounding shall be connected to the ground bus. Motor Control Centers shall be Class 1, Type B. Wiring between front unit compartments and rear-mounted equipment shall be done by the equipment supplier. All power wiring insulation shall be 90 DEG. C thermosetting material, shall be non-propagating and fire-resistant, and shall meet test requirements of NEMA WC-3, Part 6. Minimum wire size shall be No. 12 AWG for power cables and No. 14 AWG for control cables. Wire ties shall be furnished in vertical wire troughs to group and securely hold wires in place. A sufficient number of terminal blocks (TB) shall be installed to provide no less than 20 percent unused terminal points for Owner's use, distributed throughout the Motor Control Center. All connections to internal equipment shall be made on one side of the TB, and not more than two wires shall be connected under a single terminal. A combination motor control unit shall consist of an external disconnect that operates a molded-case circuit breaker and a magnetic starter. They shall be any of the following types: (a) full voltage, non-reversing, (b) full voltage reversing, or (c) full voltage, two-speed, one-winding. Feeder tap units shall be used principally for non-motor loads. They shall consist of molded-case circuit breakers. Feeder tap units shall have an interrupting or -------------------------------------------------------------------------------- EPC - Exhibit B -------------------- TENASKA GEORGIA GENERATION PROJECT Page 95 of 132 -------------------------------------------------------------------------------- short circuit rating which equals or exceeds available short circuit current at the horizontal main bus. Circuit breakers of the same frame size shall be physically interchangeable. The Contractor shall select appropriate heater sizes and furnish heater selection tables and time current characteristic curves. Short circuit withstand ratings of heaters shall also be furnished by the Contractor. Overload relays shall be provided with a manual reset bar for operation from outside the enclosure. Heater elements shall be front accessible. By changing heater elements, it shall be possible to change relay ratings with ease. The heater element design shall permit its installation only in the proper position (e.g. not backwards, facing out of the overload relay). Heater characteristic curves shall closely resemble the temperature rise curve of standard induction motors. One normally closed overload relay contact shall be furnished in the control circuit. If an overload condition occurs in any phase, it shall cause the magnetic relay to trip the starter by opening normally closed contacts. Control power transformers shall be the pressure-molded type. The voltage ratio shall be 600/120 V ac, 60 Hz. Rated secondary current of control power transformers shall exceed the continuous duty current of the control circuit. The transformer VA rating shall be a minimum of 100 VA in excess of the requirements for the Contractor and equipment supplier needs. Each control transformer secondary circuit shall have one leg fused and the other leg grounded. The Contractor shall provide time-current characteristic curves covering all fuse sizes and types. The Contractor shall furnish safe thermal capability curves for Control Power Transformers. Four auxiliary contacts, in addition to holding coil contacts, two normally open and two normally closed, shall be provided in each non-reversing motor starter for interlocking, PCS and Owner's use. Similarly, two auxiliary contacts, in addition to holding coil contacts, one normally open and one normally closed, shall be provided in each contactor in each reversing motor starter.

Motor Control Centers. This section covers the engineering, design, manufacture, installation and testing of indoor motor control centers. The motor Motor control centers shall supply the 480 volt station auxiliary loads. The equipment (MCCs) shall be suitable for operation on indoor, enclosed, dead‑front, freestanding units. All phase buses shall be insulated or isolated copper and shall be plated at all connection points or joints. A silver or tin plated copper ground bus shall be provided, and shall extend the full length of the MCC. MCC load feeders consist of a 480/277 voltcircuit breaker or the combination of a circuit breaker, control power transformer and magnetic contactor. Minimum starter size is Size 1. Circuit breakers shall be the molded case type. In addition, each 480V combination starter shall be provided with a three-phasephase thermal bi-metal overload relay. MCCs shall have a minimum short-circuit rating of 42,000 amps symmetrical, 60 hertz, grounded serviceand the short circuit value of the system shall be confirmed by calculation in E-tap. Motor control centers shall conform to the requirements of UL 845, NEMA ICS1, NEMA ICS2, NEMA ICS4, and NEMA ICS6. Each Motor Control Center shall consist of one or more vertical sections and center wiring shall be designed to permit future additionsClass I, changesType B, or regroupingper NEMA ICS 2. As a minimum, one equipped spare space for a size 2 starter 5% spares shall be provided for each vertical section. In additionstarter size used, with a minimum of one spare combination starter of each size and -------------------------------------------------------------------------------- EPC - Exhibit B -------------------- TENASKA GEORGIA GENERATION PROJECT Page 93 of 132 -------------------------------------------------------------------------------- type less than size 5 shall be supplied in each Motor Control Center. The Motor Control Center assembly shall be of a nonventilating type. All enclosure vertical sections shall be mounted on continuous front and back channel iron xxxxx and bolted firmly together to form a rigid, freestanding, dead-front, completely enclosed, front line assembly. Vertical sections shall be formed of manufacturer's standard gauge sheet steel with uniform, blemish-free surfaces. Each vertical section may contain a maximum of six unit compartments. End sections shall have removable end closing plates, and provisions shall be provided for access to horizontal bus and horizontal wireways. Easily removable blank hinged doors shall cover all unused unit spaces. Bolted covers shall be furnished on the rear of the section. The vertical bus and its insulation in the rear section shall be covered with sheet metal plates suitable for mounting control and other devices. Conduit entrance space and wire entry room greater or equal to cross-sectional area of vertical wireways shall be provided at both the top and bottom of each section. Top and bottom horizontal wireways with full length continuity shall be provided. Wireways shall be isolated from the bus bars by barriersused per unit. A vertical wireway shall extend from the top horizontal wireway to the bottom horizontal wireway for the purpose minimum of routing cables to control units. The wireway shall be isolated from all units and the bus bars to guard against accidental contact. A separate hinged door shall cover the vertical wireway for easy and safe access to wiring without disturbing control units. The vertical wireway shall be greater than a 24 square inch cross sectional area. The vertical wireway shall have one hole, two inches or larger per unit compartment, for cables from the rear of the section to unit compartments. Hole edges shall be suitably covered to safeguard against injury to cables. Each unit compartment shall have a front door, securely mounted with rugged hinges which allow the door to swing open to facilitate maintenance. Unit doors shall be fastened to the stationary structure so they may be closed to cover the unit space when the units have been temporarily removed. A panel for any required pilot devices shall be attached to the control unit, not the unit compartment door. Panels for pilot devices shall be furnished even when pilot devices are not originally specified for control units. Motor starting and feeder tap unit doors shall be interlocked mechanically with the unit disconnect device to prevent unintentional opening of the door while energized and unintentional application of power while the door is open. Means shall be provided for releasing the interlock for intentional operation while the door is open. Provision shall be made to lock the disconnect device in the OFF position with two separate padlocks. The unit disconnect operating switch shall not be mounted on the unit door. The disconnect switch shall indicate ON, OFF, and automatic trip position with the door open or closed. Means shall be provided for padlocking the unit in the partially withdrawn and disconnected positions. -------------------------------------------------------------------------------- EPC - Exhibit B -------------------- TENASKA GEORGIA GENERATION PROJECT Page 94 of 132 -------------------------------------------------------------------------------- Each plug-in unit shall be supported and guided so that unit installation is easily accomplished. Support and guidance devices shall be easily transferred from one location to another to facilitate rearrangement of the Motor Control Center. Each unit shall be isolated from the bus compartment, wireways, and adjacent unit compartments by grounded sheet metal barriers. Hand holds shall be provided on each unit to facilitate installation and removal. Wireway holes shall be grommeted. A continuous main three-conductor copper horizontal bus shall be provided over the full length of the control center. Buses shall be mounted edgewise and supported on insulated bus supports. Front removable or sliding barriers shall be provided to prevent accidental contact with the horizontal bus. Bus bars, removable top plate, and all bolted connections shall be accessible from the front of each vertical section. The main horizontal bus and vertical bus rating shall be minimum 600 amp and 300 amp rms continuous, respectively. All buses shall be braced for an rms symmetrical interrupting current consistent with the electrical system design (e.g. 25,000 or 42,000 amps). A continuous copper ground bus capable of carrying short circuit current shall be rigidly bolted to the structure across the full length of the Motor Control Center. Equipment requiring grounding shall be connected to the ground bus. Motor Control Centers shall be Class 1, Type B. Wiring between front unit compartments and rear-mounted equipment shall be done by the equipment supplier. All power wiring insulation shall be 90 DEG. C thermosetting material, shall be non-propagating and fire-resistant, and shall meet test requirements of NEMA WC-3, Part 6. Minimum wire size shall be No. 12 AWG for power cables and No. 14 AWG for control cables. Wire ties shall be furnished in vertical wire troughs to group and securely hold wires in place. A sufficient number of terminal blocks (TB) shall be installed to provide no less than 20 percent unused 20% spare terminal points for Owner's use, distributed throughout the Motor Control Center. All connections to internal equipment shall be made on one side of the TB, and not more than two wires shall be connected under a single terminal. A combination motor control unit shall consist of an external disconnect that operates a molded-case circuit breaker and a magnetic starter. They shall be any of the following types: (a) full voltage, non-reversing, (b) full voltage reversing, or (c) full voltage, two-speed, one-winding. Feeder tap units shall be used principally for non-motor loads. They shall consist of molded-case circuit breakers. Feeder tap units shall have an interrupting or -------------------------------------------------------------------------------- EPC - Exhibit B -------------------- TENASKA GEORGIA GENERATION PROJECT Page 95 of 132 -------------------------------------------------------------------------------- short circuit rating which equals or exceeds available short circuit current at the horizontal main bus. Circuit breakers of the same frame size shall be physically interchangeable. The Contractor shall select appropriate heater sizes and furnish heater selection tables and time current characteristic curves. Short circuit withstand ratings of heaters shall also be furnished by the Contractor. Overload relays shall be provided with a manual reset bar for operation from outside the enclosure. Heater elements shall be front accessible. By changing heater elements, it shall be possible to change relay ratings with ease. The heater element design shall permit its installation only in the proper position (e.g. not backwards, facing out of the overload relay). Heater characteristic curves shall closely resemble the temperature rise curve of standard induction motors. One normally closed overload relay contact shall be furnished in the control circuit. If an overload condition occurs in any phase, it shall cause the magnetic relay to trip the starter by opening normally closed contacts. Control power transformers shall be the pressure-molded type. The voltage ratio shall be 600/120 V ac, 60 Hz. Rated secondary current of control power transformers shall exceed the continuous duty current of the control circuit. The transformer VA rating shall be a minimum of 100 VA in excess of the requirements for the Contractor and equipment supplier needs. Each control transformer secondary circuit shall have one leg fused and the other leg grounded. The Contractor shall provide time-current characteristic curves covering all fuse sizes and types. The Contractor shall furnish safe thermal capability curves for Control Power Transformers. Four auxiliary contacts, in addition to holding coil contacts, two normally open and two normally closed, shall be provided in each non-reversing motor starter for interlockingstarter. If smart MCCs are used, PCS and Owner's use. Similarly, two auxiliary contacts, in addition to holding coil contacts, one normally open and one normally closed, Class II Type C wiring shall be provided provided. Motors connected to 480V power centers and MCCs shall be rated 460V. Motor operated valves shall be fed from MCC starters if the FVR starters are not furnished with the MOVs. Any remote MCCs shall have NEMA 3R walk-in enclosures supplied with filtered ventilation openings with fans, and space heaters. Combination starters shall consist of magnetic-only circuit breakers and starters. Each starter shall be furnished with individual fused and grounded control power transformer, 2NO and 2NC, plus seal-in auxiliary interlocks. The use of “Smart MCCs” (MCCs with integral remote logic) is acceptable, providing the switchgear supplier has demonstrated a proven system suitable for interconnection with the plant DCS system. If used for control and serial linked between the MCC and the Plant DCS, this system requires redundant fiber optic data paths routed through independent raceway minimizing single failure probability. Space heaters shall be furnished at the bottom of each contactor in each reversing vertical section of all outdoor motor startercontrol centers to prevent condensation of moisture within the enclosures.

Motor Control Centers. This section covers the engineering, design, manufacture, installation and testing of indoor motor control centers. The motor control centers shall supply the 480 volt station auxiliary loads. The equipment shall be suitable for operation on a 480/277 volt, three-phase, 60 hertz, grounded service. Motor control centers (MCCs) shall conform to the requirements of UL 845be indoor, NEMA ICS1enclosed, NEMA ICS2dead‑front, NEMA ICS4, and NEMA ICS6freestanding units. Each Motor Control Center All phase buses shall consist of one be insulated or more vertical sections isolated copper and shall be designed to permit future additions, changes, plated at all connection points or regrouping. As a minimum, one equipped spare space for a size 2 starter shall be provided for each vertical section. In addition, one spare combination starter of each size and -------------------------------------------------------------------------------- EPC - Exhibit B -------------------- TENASKA GEORGIA GENERATION PROJECT Page 93 of 132 -------------------------------------------------------------------------------- type less than size 5 shall be supplied in each Motor Control Center. The Motor Control Center assembly shall be of a nonventilating type. All enclosure vertical sections shall be mounted on continuous front and back channel iron xxxxx and bolted firmly together to form a rigid, freestanding, dead-front, completely enclosed, front line assembly. Vertical sections shall be formed of manufacturer's standard gauge sheet steel with uniform, blemish-free surfaces. Each vertical section may contain a maximum of six unit compartments. End sections shall have removable end closing plates, and provisions shall be provided for access to horizontal bus and horizontal wireways. Easily removable blank hinged doors shall cover all unused unit spaces. Bolted covers shall be furnished on the rear of the section. The vertical bus and its insulation in the rear section shall be covered with sheet metal plates suitable for mounting control and other devices. Conduit entrance space and wire entry room greater or equal to cross-sectional area of vertical wireways shall be provided at both the top and bottom of each section. Top and bottom horizontal wireways with full length continuity shall be provided. Wireways shall be isolated from the bus bars by barriersjoints. A vertical wireway shall extend from the top horizontal wireway to the bottom horizontal wireway for the purpose of routing cables to control units. The wireway shall be isolated from all units and the bus bars to guard against accidental contact. A separate hinged door shall cover the vertical wireway for easy and safe access to wiring without disturbing control units. The vertical wireway shall be greater than a 24 square inch cross sectional area. The vertical wireway shall have one hole, two inches silver- or larger per unit compartment, for cables from the rear of the section to unit compartments. Hole edges shall be suitably covered to safeguard against injury to cables. Each unit compartment shall have a front door, securely mounted with rugged hinges which allow the door to swing open to facilitate maintenance. Unit doors shall be fastened to the stationary structure so they may be closed to cover the unit space when the units have been temporarily removed. A panel for any required pilot devices shall be attached to the control unit, not the unit compartment door. Panels for pilot devices shall be furnished even when pilot devices are not originally specified for control units. Motor starting and feeder tap unit doors shall be interlocked mechanically with the unit disconnect device to prevent unintentional opening of the door while energized and unintentional application of power while the door is open. Means shall be provided for releasing the interlock for intentional operation while the door is open. Provision shall be made to lock the disconnect device in the OFF position with two separate padlocks. The unit disconnect operating switch shall not be mounted on the unit door. The disconnect switch shall indicate ON, OFF, and automatic trip position with the door open or closed. Means shall be provided for padlocking the unit in the partially withdrawn and disconnected positions. -------------------------------------------------------------------------------- EPC - Exhibit B -------------------- TENASKA GEORGIA GENERATION PROJECT Page 94 of 132 -------------------------------------------------------------------------------- Each plugtin-in unit shall be supported and guided so that unit installation is easily accomplished. Support and guidance devices shall be easily transferred from one location to another to facilitate rearrangement of the Motor Control Center. Each unit shall be isolated from the bus compartment, wireways, and adjacent unit compartments by grounded sheet metal barriers. Hand holds shall be provided on each unit to facilitate installation and removal. Wireway holes shall be grommeted. A continuous main three-conductor plated copper horizontal ground bus shall be provided over and shall extend the full length of the MCC. MCC load feeders consist of a circuit breaker or the combination of a circuit breaker, control center. Buses shall be mounted edgewise and supported on insulated bus supports. Front removable or sliding barriers shall be provided to prevent accidental contact with the horizontal bus. Bus bars, removable top platepower transformer, and all bolted connections shall be accessible from the front of each vertical section. The main horizontal bus and vertical bus rating shall be minimum 600 amp and 300 amp rms continuous, respectively. All buses shall be braced for an rms symmetrical interrupting current consistent with the electrical system design (e.g. 25,000 or 42,000 amps). A continuous copper ground bus capable of carrying short circuit current shall be rigidly bolted to the structure across the full length of the Motor Control Center. Equipment requiring grounding shall be connected to the ground bus. Motor Control Centers shall be Class 1, Type B. Wiring between front unit compartments and rear-mounted equipment shall be done by the equipment supplier. All power wiring insulation shall be 90 DEG. C thermosetting material, shall be non-propagating and fire-resistant, and shall meet test requirements of NEMA WC-3, Part 6magnetic contactor. Minimum wire starter size shall be No. 12 AWG for power cables and No. 14 AWG for control cables. Wire ties shall be furnished in vertical wire troughs to group and securely hold wires in place. A sufficient number of terminal blocks (TB) shall be installed to provide no less than 20 percent unused terminal points for Owner's use, distributed throughout the Motor Control Center. All connections to internal equipment shall be made on one side of the TB, and not more than two wires shall be connected under a single terminal. A combination motor control unit shall consist of an external disconnect that operates a molded-case circuit breaker and a magnetic starter. They shall be any of the following types: (a) full voltage, non-reversing, (b) full voltage reversing, or (c) full voltage, two-speed, one-winding. Feeder tap units shall be used principally for non-motor loads. They shall consist of molded-case circuit breakers. Feeder tap units shall have an interrupting or -------------------------------------------------------------------------------- EPC - Exhibit B -------------------- TENASKA GEORGIA GENERATION PROJECT Page 95 of 132 -------------------------------------------------------------------------------- short circuit rating which equals or exceeds available short circuit current at the horizontal main busis Size 1. Circuit breakers of the same frame size shall be physically interchangeablethe molded case type. The Contractor shall select appropriate heater sizes and furnish heater selection tables and time current characteristic curves. Short circuit withstand ratings of heaters shall also be furnished by the Contractor. Overload relays In addition, each 480V combination starter shall be provided with a manual reset bar for operation from outside three-phase thermal bi-metal overload relay. MCCs shall have a minimum short-circuit rating of 42,000 amps symmetrical, and the enclosure. Heater elements short circuit value of the system shall be front accessibleconfirmed by calculation in E-tap. By changing heater elements, it Motor control center wiring shall be possible to change relay ratings with easeClass I, Type B, per NEMA ICS 2. The heater element design shall permit its installation only in the proper position (e.g. not backwardsFor each starter size used, facing out of the overload relay). Heater characteristic curves shall closely resemble the temperature rise curve of standard induction motors. One normally closed overload relay contact 5% spares shall be furnished in the control circuit. If an overload condition occurs in any phaseprovided, it shall cause the magnetic relay to trip the starter by opening normally closed contacts. Control power transformers shall be the pressure-molded type. The voltage ratio shall be 600/120 V ac, 60 Hz. Rated secondary current of control power transformers shall exceed the continuous duty current of the control circuit. The transformer VA rating shall be with a minimum of 100 VA in excess one spare of the requirements for the Contractor and equipment supplier needseach size used per unit. Each control transformer secondary circuit shall have one leg fused and the other leg grounded. The Contractor shall provide time-current characteristic curves covering all fuse sizes and types. The Contractor shall furnish safe thermal capability curves for Control Power Transformers. Four auxiliary contacts, in addition to holding coil contacts, two normally open and two normally closed, A minimum of 20% spare terminal points shall be provided in each non-reversing motor starter for interlockingstarter. If smart MCCs are used, PCS and Owner's use. Similarly, two auxiliary contacts, in addition to holding coil contacts, one normally open and one normally closed, Class II Type C wiring shall be provided provided. Motors connected to 480V power centers and MCCs shall be rated 460V. Motor-operated valves shall be fed from MCC starters if the FVR starters are not furnished with the MOVs. Any remote MCCs shall have NEMA 3R walk-in enclosures supplied with space heaters and filtered ventilation openings with fans. Combination starters shall consist of magnetic-only circuit breakers and starters. Each starter shall be furnished with individual fused and grounded control power transformer, 2NO and 2NC, plus seal-in auxiliary interlocks. The use of “Smart MCCs” (MCCs with integral remote logic) is acceptable, providing the switchgear supplier has demonstrated a proven system suitable for interconnection with the plant DCS system. If used for control and serial linked between the MCC and the Plant DCS, this system requires redundant fiber optic data paths routed through independent raceway to minimize single failure probability. Space heaters shall be furnished at the bottom of each contactor in each reversing vertical section of all outdoor motor startercontrol centers to prevent condensation of moisture within the enclosures.