IB140012EN
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Instructional Booklet
Effective: March 2021
Page
35
Operation and Maintenance Manual,
Automatic Transfer Switch Controller, ATC-900
Feature 5K:
Overvoltage Monitoring for Source 2
This feature constantly monitors Source 2 for an overvoltage con-
dition. When the Source 2 voltage rises to a value equal to or
above the overvoltage dropout setting, the source will become
unavailable. The source’s voltage will then have to drop to a value
that is equal to or below the pickup setting to become available
again. This can be disabled in the setpoint settings under menu 1
in the Setpoints Dropouts/Pickups.
Overfrequency Monitoring for Source 2
This feature constantly monitors Source 2 for an overfrequency
condition. When the Source 2 frequency rises to a value equal to
or above the overfrequency dropout setting, the source will
become unavailable. The source’s frequency will then have to
drop to a value that is equal to or below the pickup setting to
become available again. This can be disabled in the setpoint set-
tings under menu 2 in the Setpoints Dropouts/Pickups.
Feature 5L:
Voltage Unbalance Monitoring for Source 2
This feature constantly monitors Source 2 for a voltage unbalance
condition using symmetrical components calculations. When the
ratio of negative sequence to positive sequence voltage (V2/V1)
exceeds the unbalance dropout setting the Unbalance/Phase Loss
time delay starts counting. If the timer expires before the unbal-
ance is resolved the source will become unavailable. The unbal-
ance must drop to a value that is below the pickup setting to stop
the timer or to become available after the timer expires. This can
be disabled in the setpoint settings under menu 3 in the Setpoints
Dropouts/Pickups.
Feature 5M: Voltage Phase Loss for Source 2
This feature constantly monitors Source 2 for a phase loss condi-
tion using symmetrical components voltage calculations. When
the ratio of negative sequence to positive sequence voltage (V2/
V1) exceeds the phase loss dropout setting the Unbalance/Phase
Loss time delay starts counting. If the timer expires before the
phase loss is resolved the source will become unavailable. The
phase loss must drop to a value that is below the pickup setting
to stop the timer or to become available after the timer expires.
This can be disabled in the setpoint settings under menu 3 in the
Setpoints Dropouts/Pickups.
Feature 7B: Time Delay Engine Fail
TDEF (0 to 60 seconds) is used where at least one source is an
engine generator, TDEF will delay an available source from being
declared unavailable in order to override momentary generator
fluctuations. This time delay is only implemented when the load is
connected to a generator source. TDEF is not displayed when the
number of generators is zero. TDEF is used for both generators in
the Dual Generator mode.
Feature 8C/8D: Transfer Time Delay Bypass
This feature allows a pushbutton input to be used to bypass the
timer for standard feature (TDNE) or standard feature (TDEN) indi-
vidually, or both simultaneously. This pushbutton is on the front
of the controller (pushing "Enter" and "Help" at the same time.
One could also wire in a pushbutton remote switch to any of the
Inputs to do the same function. This feature is usually used in
testing when it is not desirable to wait for completion of the tim-
ing sequence.
Feature 9B: Maintenance Mode (Monitor Mode)
This is a two position switch that is labeled Maintenance Mode for
breakers, power breakers (MG) and Monitor Mode for contractors.
This will place the controller in Monitor Mode and no transfers will
occur and the controller will continue to monitor the availability,
connected state, and voltages.
Feature 9C Monitor
This is a two position switch that will place the controller into
Monitor. It will use one of the inputs of the controller and is used
for contactors. When used, no transfers will occur and the con-
troller will continue to monitor the availability, connected state,
and voltages.
Feature 10A: Preferred Source Selection
This feature permits the selection of either source (1, 2 or None,
or External) as the Preferred (or Normal) Source. The Normal
Source is the source that the switch always looks to for availabil-
ity so that it can transfer to it. When two generators are selected
and the switch has transferred to the Emergency Source, the
ATC-900 will constantly be waiting and attempting to start the
generator on the Preferred Source so that it may return to it. If
NONE is chosen, the Preferred Source or the Normal Source will
be the source that is presently attached to the load. This can be
changed in the controller setpoints or one may wire up a two posi-
tion switch into one of the programmable inputs (controller set-
point must be set to External).
Feature 15G & 15H
This feature, mainly for contactors, are Source Position Contacts
(to Terminal Blocks) for Source 1 and Source 2. Up to 10 each
position contacts for Source 1 and Source 2 may be obtained
using the outputs of the controller and the I/O Modules if desired.
15G and 15H are contacts which indicate to the position even if
power is removed. For Closed Transition type switches these are
always available. For Open type switches, 15G and 15H are an
option.
Feature 16: External Overcurrent Protection
When integral overcurrent protection is provided for either one or
both sources, the need for separate upstream overcurrent protec-
tion (in most instances) is eliminated. With this factory installed
feature in the ATC-900, further automatic transfer operation is
locked-out until the appropriate source breaker is reset. It will
continue to monitor the voltage availability and the switch posi-
tions.
Feature 16T: Load Current Unbalance Monitoring
(must have option 18J DCT Module)
This feature constantly monitors the load current for an unbalance
condition using symmetrical components calculations. The current
unbalance enable threshold is used to avoid spurious unbalance
detections under light loads. The unbalance calculations are not
performed until the average load current exceeds this threshold.
When the ratio of negative sequence to positive sequence current
(I2/I1) exceeds the unbalance dropout setting the Unbalance/
Phase Loss time delay starts counting. If the timer expires before
the unbalance is resolved the connected source will become
unavailable. The unbalance must drop to a value that is below the
pickup setting to stop the timer or to become available after the
timer expires. This can be disabled in the setpoint settings under
menu 3 in the Setpoints Dropouts/Pickups.
