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Chapter 21 Station Service Electrical System
EM 1110-2-3105
30 Mar 94
Chapter 21
Station Service Electrical System
21-1. Auxiliary Power Distribution
a. Low-voltage stations.
In low-voltage stations,
auxiliary
loads of 480 volts and below are most con-
veniently distributed by means of a power panel(s) either
mounted in a vertical section of the motor control center
or in a strategic location along a station wall.
This
power panel(s) should be fed from a circuit breaker or
fusible disconnect switch in the motor control center. A
separate auxiliary or lighting service may be required to
obtain the optimum rate schedule from the utility.
b. Medium-voltage stations.
In medium-voltage
stations, packaged unit substations are available that
conveniently incorporate a high-voltage load interrupter
switch, a 4160/480-volt transformer section, and a power
panel section.
It is not necessary to provide a main
breaker on the power panel since the high-voltage inter-
rupter switch provides a disconnecting means.
Three-
phase voltmeters should be provided to monitor the
480-volt service. A separate auxiliary or lighting service
may be required to obtain the optimum rate schedule
from the utility.
21-2. Lighting System
In general, 208/120-volt, three-phase, four-wire systems
are recommended for lighting loads.
A minimum of
20-percent spare circuits should be provided for future
expansion. Operating floor lights, floodlights, and other
lights that may be used for considerable periods of time
should usually be of the high-pressure sodium-type due
to their efficiency.
Where possible, several operating
floor fixtures should be furnished with quartz restrike
lamps, automatically switched so that light is available
immediately upon energization or during restrike.
If
selected fixtures do not have quartz restrike as an option,
several incandescent fixtures should be provided for this
purpose.
Following are typical foot-candle levels for
various pumping station areas:
Location
LUX
(Foot-candles)
Operating Floor
325
30
Control Room
540
50
Lavatory
215
20
Sump Catwalk
215
20
Forebay
55
5
Roadway
10
1
21-1