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Instruction Booklet
Effective: April 2006 Page 17
ATC-300 Automatic
Transfer Switch Controller
Generator Start Relay
This latching relay is the generator start relay for system configu-
rations that employ a generator as the Source 2 power source.
This relay provides a Form A contact of silver alloy with gold
flashing for closure of the generator start circuit.
The Form A contact is implemented with the Common Pin (J-5,
Pin 13) and the Normally Open Pin (J-5, Pin 14). The generator
start relay contacts are rated for 5 A, 1/6 HP @ 250 Vac. The
DC rating is 5 A @ 30 Vdc with a 150 W maximum load.
Alarm Relay
The alarm relay is de-energized to indicate an absence of an alarm
state and energized to indicate the presence of an alarm condi-
tion. Alarm conditions include the following.
1. Improper circuit breaker operation (breaker fails to open or
close within six [6] seconds)
2. Motor operator failure
3. Lockout
4. Failsafe condition
5. Aborted engine test due to Source 2 unavailability
6. Aborted plant exerciser test due to Source 2
unavailability
7. Unsuccessful in-phase transition
The alarm relay will remain energized until “Alarm Reset” is
pressed.
The full Form C contact of this relay may be wired to an alarm
annunciator panel to indicate a problem with the ATS. The full
Form C contact of this relay is implemented with the Common Pin
(J-5, Pin 8), the Normally Closed Pin (J-5, Pin 10), and Normally
Open Pin (J-5, Pin 9). The alarm relay contacts are rated for 10
A, 1-3 HP @ 250 Vac. The DC rating is 10A @ 30 Vdc.
Pre-transfer Relay
This Form C relay opens/closes on a timed basis (adjustable from
1 to 120 seconds) prior to the transfer operation between two
available sources to allow the load to be de-energized prior to
transfer in either direction. After TDNE/TDEN times out, this
relay energizes and the Pre-transfer timer (TD PRE-TRAN) starts
timing. After TD PRE-TRAN times out, the transfer proceeds.
The pre-transfer relay de-energizes after the transfer is complete.
The full Form C contact of this relay is implemented with the
Common Pin (J-5, Pin 5), the Normally Closed Pin (J-5, Pin 7),
and the Normally Open Pin (J-5, Pin 6). The pre-transfer relay
contacts are rated for 10 A, 1-3 HP @ 250 Vac. The DC rating is
10 A @ 30 Vdc.
5.5.1.2 Transfer Operations Connections
K1, K2, K3, and K4 are factory wired to operate the transfer
switch. The relay contacts for each are rated for 10 A, 1/3 HP @
250 Vac. The DC rating is 10 A @ 30 Vdc. K1 - K4 are Form C
relays but only the Form A contacts are used to operate the
transfer switch.
Note: The ATC-300 Controller MUST BE properly grounded at J-5, Pin 12
for proper operation.
Output Relay K1
This Form A relay is used for control of the transfer switch motor
to close the Source 1 breaker/switch for breaker/switch style
transfer switches. The K1 relay momentarily energizes until the
ATC-300 senses that the Source 1 breaker/switch is closed, then
K1 de-energizes. For contactor style transfer switches, this relay
opens the Source 2 contactor via its trip coil. The K1 outputs are
common pin (J-5, pin 1) and Normally Open pin (J-5, pin 2).
Output Relay K2
This Form A relay is used for control of the transfer motor to
close the Source 2 breaker/switch for breaker/switch style trans-
fer switches. The K2 relay momentarily energizes until the ATC-
300 senses that the Source 2 breaker/switch is closed, then K2
de-energizes. For contactor style transfer switches, this relay
opens the Source 1 contactor via its trip coil. The K2 outputs are
common pin (J-5, pin 3) and Normally Open pin (J-5, pin 4).
Output Relay K3
This Form A output is used for control of the close coil of the
Source 1 contactor for contactor style switches. The K3 relay
momentarily energizes until the ATC-300 senses that the Source
1 contactor is closed, then K3 de-energizes. The K3 outputs are
common pin (J-8, pin 1) and Normally Open pin (J-8, pin 2).
Output Relay K4
This Form A output is used for control of the close coil of the
Source 2 contactor for contactor style switches. The K4 relay
momentarily energizes until the ATC-300 senses that the Source
2 contactor is closed, then K4 de-energizes. The K4 outputs are
common pin (J-8, pin 3) and Normally Open pin (J-8, pin 4).
5.6 Operating Voltage and Measurements
The ATC-300 Controller operates with control power from
65 to 145 Vac. The ATC-300 operates on single and three phase
systems with selectable frequency settings of 50 or 60 Hz
depending on the system ordered.
The ATC-300 can perform the time delay engine start function
without control power. This is accomplished by the use of a
supercap and a latching control relay. The supercap stays
charged for several minutes to power the logic circuitry that pro-
vides the start pulse to the latching control relay. The latching
control relay, which controls the generator, only changes state
when it receives start or stop pulses. The coil voltage for the
latching relay comes from another capacitor that also stays
charged for several minutes.
The ATC-300 Controller operates directly from the line sensing
inputs of the Source 1 and Source 2 power sources. The nominal
operating system inputs are from 120 to 600 Vac. The standard
system assumes that neutral is available and that the transfer
motor can therefore be powered from an available 120 Vac
source. If a neutral conductor is not available, a 120 Vac supply
is created by an external transformer.
All voltage monitoring and measurements are true RMS measure-
ments.
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