TP-6714 4/10 13Section 1 Installation
1.2 Extended Transfer Time Relay
The extended transfer time relay is provided on
closed-transition transfer switches. The relay is
provided to prevent paralleling the standby and utility
sources for longer than the acceptable time if the
closed-transition transfer time exceeds 100 ms.
See the transfer switch installation manual for
connection instructions.
The relay operation time is adjustable between 100 ms
and 10 seconds. The time settings are in percent (%) of
the maximum setting, which is 10 seconds, and
adjustable in 5% increments. See Figure 1-4. The
recommended setting is 1% = 0.1 seconds. If it is
necessary to set the relay to a longer time, ensure that
the time setting is in accordance with applicable codes.
The relay activates only if the closed-transition transfer
time exceeds the set time. A Fail to Open Source1 (or
Source2) fault message will display on the ATS
controller. Identify and correct the cause of the source
disconnect problem before resetting the fault.
Setting* Time
1% 0.1 seconds (100 ms)
50 % 5 seconds
100 % 10 seconds
* Settings above 1% are adjustable in 5% increments.
Figure 1-4 Relay Transfer Time Settings
1. Extended transfer time relay
1
TP-6714
Figure 1-5 Extended Transfer Time Relay
1.3 Accessory Connections
See Section 8 and the transfer switch wiring diagrams
for accessory connection instructions.
1.4 Controller Powerup/Reset
Following is an explanation of the sequence of operation
for the MPACt 1500 ATS Controller when power is
initially applied to the controller or a controller reset
occurs.
1. Controller self test is executed.
2. System parameters are downloaded from
nonvolatile memory.
3. Contactor position and source availability are
determined.
4. If neither source is acceptable, the contactor does
not change position.
5. If both sources are available, the controller
immediately transfers the contactor to the
preferred source.
6. If only one source is available, the controller
immediately transfers the contactor to that source,
executing only the off-position and load control
time delays.
If the available source is the preferred source, and
the contactor is in the standby position, the
contactor transfers to preferred, the engine
cooldown time delay runs, and then the engine
start contacts open.
If the available source is the preferred source and
the contactor is already in the preferred position,
the engine start contacts open immediately,
bypassing the engine cooldown time delay.
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