Switchgear and Load Centers

DOE-HDBK-6004-99

The safety-class diesel generators (or combustion turbine generators) should be designed in

accordance with the requirements of USNRC Regulatory Guide 1.9 and should meet the requirements

of IEEE-387 Standard. The capacity of diesel generators (or combustion turbine generators) should

be sufficient to accommodate all safety-class loads as defined in fusion facility safety analysis.

There should be no direct interconnections between the emergency/back-up electrical power sources

of the facility. There should be no provisions for automatically paralleling these power sources within

the facility, and administrative control should be provided to prevent manual paralleling of these

power sources. Provisions should be made for auto/manual synchronizing each emergency/back-up

power source, to its respective bus for periodic testing during normal facility operation.

Each emergency/back-up power source and its auxiliaries should be located in seismically qualified

separate rooms.

After start initiation, the power source, diesel or combustion turbine generator, should accelerate to

and stabilize at synchronous speed with rated frequency/voltage within the time period specified in

the safety analysis, and accept the first block of loads.

The safety-class diesel generators should be manufactured and tested in accordance with ANSI

Standards C50.10 and C50.12, NEMA Standard Publication MG-1, and IEEE Standards 115 and

386.

If an alternative type of power source is chosen, e.g. a dam and hydroelectric turbine, it should be

manufactured and tested according to the requirements of procurement specifications.

Switchgear and Load Centers

The switchgear should be fully rated for the maximum expected short-circuit current and continuous

current capacity. All switchgear breakers should be drawout type, electrically operated, stored energy

air circuit breakers.

The electrical equipment with 480 V or higher for the safety-class systems should be designed and

qualified in accordance with IEEE Standards 344 and 323 for Class 1E electrical equipment.

Fault calculations should be made in accordance with the latest issue of ANSI Standards C37.010 and

C37.13.

Selected high voltage switchgear breakers including 480V should be provided with local control in

addition to the remote control in the control room and the automatic controls. The control voltage

should be 125 VDC.

All switchgear and load centers should be located indoors. Access space should be provided in back

and in front of the switchgear and load centers as recommended by the manufacturer.

Large 480V loads (60 through 250-hp motor loads, 100 through 400-kW non-motor loads) and

motor control centers should be supplied from 480V load centers. Each load center should be

provided with 4160 to 480V, 3-phase, 60 Hz, dry type transformer, with a 60 kV Basic Impulse Level

(BIL) primary rating. "De-energized change" taps should be provided the same as specified for the