IB140012EN
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Instructional Booklet
Effective: March 2021
Page
5
Operation and Maintenance Manual,
Automatic Transfer Switch Controller, ATC-900
Also with Closed Transition and In-Phase disabled:
TDN or LVD
The user setpoints for closed transition are similar to this:
•
Disabled (Closed transition not used)
•
Alarm on Synchronization Fail (Will not switch and will show
an alarm)
•
Fallback to Open on Synchronization Fail (To in-phase, TDN,
and/or LVD)
For In-Phase and Closed transfers, the phase difference between
sources (synchroscope) is displayed with the ATC-900's Sync
Time countdown message.
Feature 47C: Closed/In-phase Transition/Load Voltage Decay
Closed Transition is a feature that will temporarily parallel two live
sources in a make-before-break scheme when performing a trans-
fer. This achieves a transfer between sources with no power
interruption. Both sources must be synchronized in frequency,
phase, and voltage before the transfer is initiated.
In-phase transition is a feature that will allow a transfer between
two live sources only when the phase difference between the two
sources is near zero. This is an open transition transfer that pre-
vents in-rush currents from exceeding normal starting currents in
the case where motor loads are being transferred.
Load Voltage Decay utilizes the load voltage measurements to
sense back EMF that is generated when the transfer switch is in
the neutral position. It provides a delay in transfer in either direc-
tion if an unacceptable level is sensed as established by a cus-
tomer programmed level. The transfer will not take place until the
back EMF decays below the acceptable programmed level. This
feature has a separate setting of enabling or disabling the opera-
tion. If disabled, the transfer switch will not delay in the neutral
position and will transfer between the sources as fast as possible.
Feature 47D: Closed Transition Only
Closed Transition is a feature that will temporarily parallel two live
sources in a make-before-break scheme when performing a trans-
fer. This achieves a transfer between sources with no power
interruption. Both sources must be synchronized in frequency,
phase, and voltage before the transfer is initiated. If the two avail-
able sources do not synchronize in a certain settable sync time,
the switch will not transfer and an output alarm will be present as
well as a red flashing banner on the controller stating; Failed to
Sync -(Frequency, Voltage, or Phase angle)
If the logic is forced into a fail safe mode (i.e. loss of connected
source), the logic will perform an open transfer.
Optional Feature 47E: Closed/In-Phase Transition/Time Delay
Neutral
Closed Transition is a feature that will temporarily parallel two live
sources in a make-before-break scheme when performing a trans-
fer. This achieves a transfer between sources with no power
interruption. Both sources must be synchronized in frequency,
phase, and voltage before the transfer is initiated.
In-phase transition is a feature that will allow a transfer between
two live sources only when the phase difference between the two
sources is near zero. This is an open transition transfer that pre-
vents in-rush currents from exceeding normal starting currents in
the case where motor loads are being transferred.
Time delay neutral provides a time delay in the transfer switch
neutral position when both breakers/contactors are open. This
delay takes place when the load is transferred in either direction to
prevent excessive in-rush currents due to out of phase switching
of large motor loads.
Feature 47F: Closed/Load Voltage Decay
Closed Transition is a feature that will temporarily parallel two live
sources in a make-before-break scheme when performing a trans-
fer. This achieves a transfer between sources with no power inter-
ruption. Both sources must be synchronized in frequency, phase,
and voltage before the transfer is initiated.
Time Delay Load Voltage Decay utilizes the load voltage measure-
ments to sense back EMF that is generated when the transfer
switch is in the neutral position. It provides a delay in transfer in
either direction if an unacceptable level is sensed as established
by a customer programmed level. The transfer will not take place
until the back EMF decays below the acceptable programmed
level. This feature has a separate setting of enabling or disabling
the operation. If disabled, the transfer switch will not delay in the
neutral position and will transfer between the sources as fast as
possible.
Feature 47G: Closed/Time Delay Neutral
Closed Transition is a feature that will temporarily parallel two live
sources in a make-before-break scheme when performing a trans-
fer. This achieves a transfer between sources with no power inter-
ruption. Both sources must be synchronized in frequency, phase,
and voltage before the transfer is initiated.
Time delay neutral provides a time delay in the transfer switch
neutral position when both breakers/contactors are open. This
delay takes place when the load is transferred in either direction to
prevent excessive in-rush currents due to out of phase switching
of large motor loads.
Optional Feature 29G: Type of Operation (Selectable Automatic or
Non-Automatic)
This feature provides two door mounted selector switches marked
Auto/Manual and S1-Trip-S2 which permits the selection of auto-
matic or manual operation. In manual operation, the user can man-
ually initiate and electrically operate between S1, Trip, or S2. On
the Contactor Bypass's, 29G uses the top switch and the bottom
switch. The newer contactor bypasses (some starting in 2018)
have 29G integrated and standard for either the ATS or the
Bypass contactors. See the switch instruction booklet for operat-
ing instructions. The controller is in Monitor Mode during the
manual operation meaning the controller will not attempt to
change the switch position but will monitor the voltage availability
and the switch positions. The ATC-900's display will show "MON-
ITOR".