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Instruction Booklet
Page 6 Effective: April 2006
ATC-300 Automatic
Transfer Switch Controller
26. Source 1 - Monitoring and Protection
This feature provides Source 1 monitoring and protection
functions. If the Source 1 power supply fails, then the
ATC-300 will begin the sequence of operations necessary
to transfer the load circuit to the Source 2 power source.
All Feature 26 monitoring and protection functions are
“failsafe” operations.
26A. All Phase Undervoltage Protection
This feature provides all phase undervoltage monitoring and
protection.
Adjustable Undervoltage:
Dropout (Breaker Style): 50-97% of nominal
Dropout (Contactor Style): 78 - 97% of nominal
Pickup: (Dropout +2%) to 99% of nominal
26C. All Phase Overvoltage Protection
Provides all phase overvoltage monitoring and protection.
Adjustable Overvoltage:
Dropout (Breaker Style): 105-120% of nominal
Dropout (Contactor Style): 105-110% of nominal
Pickup: (Dropout -2%) - 103% of nominal
26D. Go to Source 2
This feature provides the capability for an external contact
opening to initiate a load power transfer to the Source 2
power source. This includes starting the engine/generator,
performing the programmed time delays, and the transfer
operation. Re-transfer will occur when the external contact
is closed or under a “failsafe” condition. A connection
point on the controller for the connection of an external
contact is included.
26E. All Phase Underfrequency Protection
Provides all phase underfrequency monitoring and protec-
tion.
Adjustable Underfrequency:
Dropout: 90-97% of nominal
Pickup: (Dropout +1Hz) to 99% of nominal
26F. All Phase Overfrequency Protection
Provides all phase overfrequency monitoring and protec-
tion.
Adjustable Overfrequency:
Dropout (Breaker Style): 103-110% of nominal
Dropout (Contaactor Style): 103 - 105% of nominal
Pickup: (Dropout -1Hz) to 101% of nominal
26H. Phase Reversal Protection
For a 3-phase wye source, this feature monitors the phase
sequence of the sources. If a source does not have the
same ABC or CBA sequence as the phase reversal setpoint,
the source will be considered “Unavailable”.
For a 3-phase delta source, this feature should be turned
off via the PHASE REV setpoint.
26L. Source 1 3-Phase Voltage Unbalance/Loss
For a 3-phase wye source, this feature monitors phase volt-
age ratios. Voltage unbalance (%) is calculated as the dif-
ference between the maximum and minimum phase
voltage, divided by the minimum phase voltage. User-
selectable setpoints are available for dropout and pickup
unbalance settings (minimum 2% differential). Dropout is
adjustable from 5 to 20%. Pickup is adjustable from 3 to
(Dropout –2%)). A setpoint for user-selectable time delay
from 10 to 30 seconds is provided. The factory default
setpoints are: 5% dropout, 3% pickup, and 30 seconds
time delay. A user-selectable setpoint for enable and dis-
able is also provided.
When an unbalance condition is detected on Source 1, the
Unbalance Timer (TD UNBAL) starts timing. After TD
UNBAL times out, Source 1 is declared “failed”.
For a 3-phase delta source, this feature should be turned
off via the VOLT UNBAL setpoint.
29. Alternate Transfer Modes of Operation
Provides standard or optional transfer modes, mode selec-
tion devices, and operational methods for ATSs.
29A. Automatic Operation
Provides fully automatic transfer, re-transfer, and engine/
generator startup and shutdown operations.
32. Delayed Transition Transfer Modes for Open Transition
Transfer Switches
This feature provides delayed transition transfer modes for
an open transition transfer switch. Often used in systems
with inductive loads, a delayed transition transfer switch
may prevent or reduce in-rush currents due to out of
phase switching of inductive loads.
32A. Time Delay Neutral
This feature provides a time delay in the neutral position
during the transfer and re-transfer operations during which
both Source 1 and Source 2 are disconnected from the
load circuit. The time delay is programmable and is the
same for both transfer and re-transfer operations.
Adjustable 0 - 120 Seconds
35. Pre-Transfer Signal
This feature provides a signal to a remote device prior to a
re-transfer operation. It provides one Form “C” contact
(NO/NC) for interface with other equipment (typically ele-
vator controls). The contacts close/open on a timed basis
prior to transfer in either direction. After TDNE/TDEN
times out, this relay closes and the Pre-transfer Timer
(TPRE) starts timing. After the TPRE times out, the trans-
fer proceeds by starting the TDN timer if enabled. The
pre-transfer relay opens after the transfer is complete.
Adjustable 0 - 120 Seconds
35A. Pre-transfer Signal with 1 N.O. and 1 N.C. Contacts
This feature provides pre-transfer signal and includes 1
N.O. and 1 N.C. contact.
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