TS 910 TRANSFER SWITCH
PM140 REV 2 14/01/23 40 Thomson Power Systems
18.8.1.4 Fail to Transfer (In-Phase Detection)
Should the transfer switch not immediately transfer following expiry of a
normal automatic mode sequence timer (e.g. Gen Warm-up Timer, Utility
Return Timer) and
both generator and utility supplies are available, the
generator and utility supplies may not be in phase as required by the ‘in-
phase’ transfer detection sensor. Should the generator and utility supplies fail
to reach an ‘in-phase’ condition for a time period of 5 minutes, an alarm
condition will be activated. This alarm condition will cause the following events
to occur:
• In-Phase Bypass Transfer: The transfer switch will bypass the
in-phase detection circuitry and force a transfer to the intended
source. Re-transfer back to the original source will be permitted
with the Wait to Transfer alarm still present.
• ‘Wait to Transfer’ LED Flashes: the “Wait to Transfer LED will
begin flashing to indicate that the transfer switch did not detect
an ‘in-phase’ condition for a 5 minute period. The LED will flash
until the alarm condition is reset.
• ‘Alarm’ LED Activated: the ‘alarm’ LED’ will be activated. The
LED will not go out until the alarm condition is reset.
• Alarm Output Signal Activated: the output signal on customer
terminals #5 & #6 will be activated. The alarm output signal will
be terminated once the alarm condition is reset.
18.9 TEST MODES
18.9.1 UTILITY POWER FAIL SIMULATION (LOAD TEST)
To simulate a utility power failure condition, a TEST pushbutton is provided on
the front faceplate. Once the mode is initiated, the gen start will be activated.
Once the generator accelerates to nominal voltage and frequency levels, the
load will automatically transfer to the generator supply. To terminate the Test
Mode, the TEST pushbutton must be used. When the pushbutton is released the
LED light will go out and, the load will re-transfer back to the utility supply
following expiry of the Utility Return delay timer.
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