voltage limit is reached. When this event occurs, the UPS issues a set of audible and visual alarms
indicating that the DC source has a minimal capacity left and a system shutdown is imminent. Unless
utility power is restored, the output can be supported for a maximum of 2 minutes before the output of the
system shuts down. If the bypass source is available, the UPS transfers to the bypass mode instead of
shutting down.
If the input power becomes available again at any time during the discharge, K1 and K5 close and the
UPS returns to normal operation. The UPS also starts to recharge the DC source to restore the capacity.
33..33..33 BByyppaassss mmooddee
CAUTION
The critical load is not protected while the UPS is in bypass mode.
The UPS automatically switches to the bypass mode if it detects an overload, load fault, or internal failure.
The bypass source supplies the commercial AC power to the load directly. The UPS can also be
commanded to transfer to the bypass mode manually through the display. The UPS status indicated on
the display is On Bypass.
The UPS returns from the bypass mode back to normal mode, if the condition (for example overload) that
caused the transfer is cleared. If there is a condition that does not clear by itself (for example UPS internal
failure), the UPS remains on bypass operation.
Figure
8: Path of current through the UPS in the bypass mode shows the path of electrical power through
the UPS system when operating in the bypass mode.
Figure 8. Path of current through the UPS in the bypass mode
A Static switch 1 Bypass input Main power flow
B Rectifier 2 Rectifier input
Energized
C Inverter 3 Output
De-energized
EATON 93PM G2 UPS USER’S AND INSTALLATION GUIDE P-164000956
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February 2021 www.eaton.eu 2244
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