GE Industrial Solutions MX350 Instruction manual - Manual (Page 80)

5–6 MX350 AUTOMATIC TRANSFER CONTROL SYSTEM – INSTRUCTION MANUAL
CONFIGURATION SETPOINTS CHAPTER 5: SETPOINTS
Once the W timer has expired, the controller will wait until both sources are within the
allowable synchronization limits and then it will energize SCR-E to connect the load with
Source 2 while it is still connected to Source 1. Once both sources are connected to the
load, the controller will immediately energize SCR-NO and the load will be disconnected
from Source 1. The actual time during which both sources are paralleled is typically less
than 100 ms.
1.
The two sources don't become synchronized within 60 seconds while attempting to
transfer to the other source.
2. If the ATS fails to disconnect from the source from which it is transferring away and
both sources remain paralleled for more than 100ms (Open Last Closed feature is
being activated).
3. The Open Last Closed feature fails and the controller issues a shunt trip command to
the generator breaker.
SOURCE 1 POWER RESTORATION:
When Source 1 is recovering and reaches the presets as set up in the
Setpoints > Operations S1 > Settings screen, the controller initiates a re-transfer to
Source 1. In order to ensure that the utility voltage and frequency are stable before
transferring back to Source 1, the delay to Source 1 (T) timer begins to time for a period of
time as set up by the user, typically set to 30 minutes. If the user wishes to re-transfer
before the T timer has expired, he or she can highlight the timing message on the Status
screen and bypass the timer by depressing the Bypass soft key. When the T timer has
timed out or the Bypass key has been depressed, the controller will wait until both sources
are within the allowable synchronization limits and then will energize SCR-N to connect the
load with Source 1 while it is still connected to Source 2. Once both sources are connected
to the load, the controller will immediately energize SCR-EO and the load will be
disconnected from Source 2. The actual time during which both sources are paralleled is
typically less than 100 ms.
The controller maintains the engine start signal for the time period specified as the U timer
(delay to stop engine) in order to ensure proper cooling of the engine before shutting it
down. If the operator desires to turn off the engine before the U timer has expired, he or
she can highlight the timing message on the Status screen and bypass the timer by
depressing the Bypass soft key. When the U timer has timed out or the Bypass key has
been depressed, the engine start signal will be removed, causing the engine to shut down.
If both sources do not synchronize within 60 seconds, the alarm light will come on, the
banner message will display "Sync Fail - Bypass Wait", and the status screen will display
the message "Sources Out of Phase". If that is the case, the user can either continue to
wait for the sources to sync at which the controller will transfer in Closed Transition mode,
or he or she can highlight the message and then press the 'Bypass' button. In that case,
the switch will transfer back in Delayed Transition mode, meaning the load will be out of
power for the time period specified as 'Delay - Neutral to Preferred Source' or 'Delay -
Neutral to Non-Preferred Source', respectively, on the Config/Operation/Timers screen.
CAUTION
CAUTION:
The user has to make sure that the values entered for 'Delay - Neutral to Preferred
Source' and/or 'Delay - Neutral to Non-Preferred Source' are sufficient to allow rotating
loads to coast to a stop. Severe dammage to connected rotating equipment can occur
if too small of a time value is selected.
NOTE
NOTE: If the ATS fails to open the source from which it is transferring away during a closed
transition transfer and both sources remain paralleled for more than 100ms, an alarm
message with be triggered, and the source that had just been connected to the load in
parallel with the other source will attempt to open once more (a.k.a the open-last-closed
feature).