TranSystems Corporation - LGM Construction

501070099 Federal Express Oakland Sort Expansion Issued for Bid 10/11
5. Control Selector Switches (to be located behind the exterior door)
a. Auto/Manual Main-Tie-Main Breaker Control two-position selector switch
b. Open/Close two-position spring-return-to-center selector switch for each breaker (three total)
1) “Close” control only enabled if Auto/Manual control selector is in the “Manual” position
2) “Close” control is electrically interlocked to prevent both main breakers and tie breaker from
being closed concurrently.
6. Sequence of Operation – Automatic Control
a. Upon obtaining a signal from the main “A” 27/47 monitoring relay (indicating a problem with the
incoming power source), a time delay of 120 seconds (adjustable up to 600 seconds minimum)
shall be activated. If the timer times out, a “loss of power source” condition shall be latched.
b. When the signal from the main “A” 27/47 monitoring relay is no longer present (indicating that the
incoming power source has returned to acceptable operating parameters), a stabilization time
delay of 15 minutes (range adjustable from at least 1 to 60 minutes) shall be activated. If the timer
times out, the “loss of power source” condition shall be unlatched.
c. An LED indicator light shall indicate the presence of each main incoming power source.
d. “Loss of power condition” monitoring for main “B” is similar to main “A”.
e. If the control is in automatic and one main source is in a “loss of power source” condition and the
other main source is not in a “loss of power source” condition, the following sequence shall take
place:
1) The main breaker on the failed side shall open, then
2) After a 5 second delay (range adjustable from at least 1 to 30 seconds) the tie breaker shall
close.
f. While the tie breaker is closed, when the main source’s “loss of power source” condition is no
longer present, the following sequence shall take place:
3) The tie breaker shall open, then
4) After a 5 second delay (range adjustable from at least 1 to 30 seconds) the main breaker shall
close.
7. Anti-race condition interlocks shall prevent initiation of transfer if both incoming main power sources fail
concurrently.
8. Automatic transfer to an incoming main power source shall be inhibited if its 27/47 relay detects a
problem with that power source (regardless of whether or not its timers have time out).
8. No transfers will be initiated if one of the main or tie breakers trips due to an overcurrent or ground-fault
condition. All such trips must be reset before normal operations can commence.
12 KV – 480/277V SECONDARY DOUBLE-ENDED UNIT SUBSTATIONS 16371-9