MGE UPS Systems EPS 8000 - Manual (Page 42)

2.12 Forced Transfers
This section describes the normal transfer conditions and the procedures to be followed when issuing forced transfers.
CAUTION: Opening Q4S with the inverter stopped in a UPS without
maintenance bypass will disconnect the attached load.
2.12.1 Uninterrupted Transfer Conditions
To transfer the load between the UPS module output and the bypass AC input (mains 2) source without interruption,
the following conditions must be satisfied:
◗ inverter output and bypass AC input phases must be in sync
◗ Bypass AC input voltage must be within 10% of nominal
◗ Bypass AC input frequency must be within a certain programmable tolerance of nominal
Provided that both the UPS module output and bypass AC input sources meet these conditions, uninterrupted
transfers can take place. If these conditions are not met, transfers cannot take place without interruption. A forced
transfer is required.
Forced transfers require a power interruption to the load of 0.8 seconds. Before issuing a forced transfer command,
be certain that the attached load can tolerate the brief outage. The following paragraphs describe the forced transfer
procedures.
2.12.2 Forced Transfer from Bypass AC Input Source to Inverter
Start the inverter by pressing the “inverter on” button on the front panel.
On the hidden panel, press the “security” key and hold it while pressing the “forced bypass to inverter” key
(pushbutton #4). The load will be disconnected for 0.8 seconds, then connected to the inverter.
2.12.3 Forced Transfer from Inverter to Bypass AC Input
On the hidden panel, press the “security” key and hold it while pressing the “forced inverter to bypass” key (pushbutton
#5). The inverter will stop and the load will be disconnected for 0.8 seconds; then the load will be connected to the
bypass AC input source. See Figure 1-10.
Operation
EPS 8000 UPS Single Module
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