TP-6126 8/0244 Section 6 Accessories
6.3.2 Supervised Transfer Control
Switch
The supervised transfer control switch
(AUTO/MANUAL/TRANSFER switch) is a
three-position, key-operated switch that allows manual
control of load transfers. The switch has maintained
AUTO and MANUAL positions and a momentary
TRANSFER position. The key can be removed in either
the AUTO or MANUAL position. The key cannot be
removed when the switch is in the TRANSFER position.
Figure 6-4 shows the switch.
The manual mode allows the system to run on the
standby source indefinitely, even if the preferred source
is available. In manual mode, the controller is inhibited
from initiating a transfer sequence until the keyswitch is
turned to the TRANSFER position.
It is not necessary to hold the switch in the TRANSFER
position during the transfer sequence. Turn the switch
to TRANSFER and release it to initiate transfer. The
transfer sequence will proceed after the switch returns
to the MANUAL position, executing all programmed
time delays and transferring the load to the other source
if it is available.
Automatic and Non-Automatic Transfer Switches.
The switch operation differs for automatic and
non-automatic switches. An automatic transfer switch
transfers automatically to an available source if the
connected source is lost. A non-automatic transfer
switch does not transfer automatically, even if the
connected source is lost. Figure 6-5 summarizes the
switch operation.
Note: Transfer switches are built and UL-labeled as
automatic or non-automatic by the factory and
cannot be converted in the field. The supervised
transfer control switch cannot be removed from
non-automatic switches in the field.
Test and Peak Shave Operation. When the
supervised transfer control switch on an automatic
system is in the MANUAL position, pressing the Test
button or sending a peak shave command causes
transfer to the standby source. However, ending the test
or removing the peak shave signal will not cause a
transfer back to the preferred source. Move the
supervised transfer control switch to the TRANSFER
position to initiate transfer back to the preferred source.
Test and peak shave signals are ignored by
non-automatic systems when the supervised transfer
control switch is in the MANUAL position.
GM21286
Figure 6 -4 Supervised Transfer Control Switch
Switch
Position
Operation, Automatic Switches Operation, Non-Automatic Switches
AUTO D Automatically transfers to the standby source, when available, if the preferred source is lost
D Transfers back to the preferred source when it becomes available
MANUAL D Automatically transfers to an available source if the
connected source is lost
D Does not automatically transfer back to preferred
when both sources are available
D Enables the Not-in-Auto indicator
D Transfers only when the switch is manually moved
to the TRANSFER position:
D Does not automatically transfer to an available
source when the connected source is lost
D Does not automatically transfer back to
preferred when both sources are available
TRANSFER D Can use to transfer when the switch is in the
MANUAL position and both sources are available
D Initiates transfer sequence to the other source, if
available, including all programmed time delays
D Operates pre- and post-transfer load control time
delays if both sources are available
D Must use for all transfers when the switch is in the
MANUAL position
D Initiates transfer sequence to the other source, if
available, including all programmed time delays
D Operates pre- and post-transfer load control time
delays if both sources are available
Figure 6 -5 Supervised Transfer Control Switch Operation
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