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4200FA Installation and Operation Manual 91
Maintenance Bypass Procedure 10.9
NOTE: The 15-50kVA 4200 Base models do not come with an internal mechanical MBS.
Transferring to Maintenance Bypass will result in loss of power to the critical load unless an
external MPS is installed.
10.9.1 To safely set the unit in Maintenance Bypass:
1. First switch the UPS electrically to bypass by rotating the BYPASS/RUN switch to BYPASS.
2. Then mechanically engage the Maintenance Bypass Switch as follows:
a. If an internal MBS, rotate the large red Bypass Switch clockwise to the Bypass position
b. If an external MBS, follow the instructions on the MBS case or operators manual.
This prevents the UPS from being placed in parallel with commercial power.
Follow the instructions below when switching the UPS to and from Maintenance Bypass Mode.
WARNING
Failure to adhere to the following instructions could result in damage to your
equipment and/or you risk removal of power to any equipment attached to
the UPS.
10.9.2 Switch from UPS to Maintenance Bypass
1) Turn the “BYPASS/RUN” key switch on the front panel to “BYPASS." Operation of the UPS
inverter stops and the LED’s display shows:
LED
Light
On-Line/Fault
(Off)
Warning
Flashing
A/C Input
Steady Green
• the system mode message (left side of the touchscreen footer) indicates the unit is in
BYPASS Mode
• the system status message (right side of the touchscreen footer) indicates the unit is in BYP
Mode
2) Output power is now provided to the load through the Bypass circuit. While in this mode, if a
power failure occurs on the commercial power source, the UPS will lose power. Power to
the critical load device will be interrupted. The battery charging circuit and chopper circuit
remains active.
3) Verify that step one above is followed, and that the BYP LED indicator on the front panel is
illuminated.
DO NOT physically place the UPS in Maintenance Bypass with the rotary Maintenance
Bypass Switch until the touchscreen indicates the unit is in BYPASS Mode.
4) Locate the maintenance bypass rotary cam switch (middle of inner front panel of the UPS); slowly
rotate the cam switch clockwise to the “BYPASS MODE” position.