FirstLine UPS
Form No. 003-2323 Rev B
26
Manual Transfer to Bypass
Verify that the bypass input is qualified by observing that the bypass indicator is green.
While holding down the ESC key, press the up-arrow key. When the conditions are met for
a transfer to bypass (bypass input is qualified and inverter is synchronized to bypass), the
static switch will transfer the load to bypass. After a few seconds, the mimic display will
update to show this.
Manual Transfer to Inverter
This procedure enables an automatic transfer to inverter. While holding down the ESC key,
press the down-arrow key. When the conditions are met for a transfer to inverter (inverter is
running and synchronized to bypass), the static switch will transfer the load to inverter.
After a few seconds, the mimic display will update to show this.
External Bypass Arrangement
If the UPS is connected to a Staco Maintenance Bypass Switch, refer to the manual for that
product for proper operation. The MBS is equipped with a label that describes common
transfer operations and a brief summary is provided below. Bypass switches provided by
others are not recommended as they are not equipped with the proper interlocks to prevent
backfeed, a hazardous condition that can be lethal to service personnel. Use of a non-
Staco bypass switch may void the UPS product warranty.
The normal mode of operation (i.e. not bypass) requires that switches 1 and 3 in the MBS
are closed. The UPS should be operating in this state. To transfer operation of the load to
Maintenance Bypass mode, first perform a manual transfer to bypass per the procedure
above. Verify that the mimic display changes to show that the load is now connected to the
bypass line. Close Switch 2 in the MBS, then open Switch 3. Turn off the UPS, if desired,,
then open Switch 1.
To return from Maintenance Bypass to Normal mode, close Switch 1 and start the UPS,
Select manual Transfer to Bypass mode. Verify that the UPS is running and that the mimic
diagram shows that the output is being supplied from the bypass line. Close Switch 3, then
open Switch 2. Select Automatic Transfer to Inverter per the procedure below.
If the UPS fails to start and it is desired to get power to the load, open Switches 1 and 3 on
the MBS, then close Switch 2. The load is now powered from the bypass, Note that the
UPS logic is not involved in the decision to apply bypass power to the load, so there is no
assurance that the bypass source is suitable for powering the load. This procedure is
performed at the user’s risk. Also note that the UPS will not start when the bypass source is
out of specification.
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