MGE UPS Systems EPS 7000 - Manual (Page 48)

2.11 Forced Transfers
This section describes the normal transfer conditions and the procedures to be followed when issuing forced transfers.
CAUTION: Using the forced transfer functions will cause the load to
experience an interruption for a minimum of 0.8 seconds. Be
certain the load can tolerate this interruption.
2.11.1 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:
◗
UPS module 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.
2.11.2 Forced Transfer from Bypass AC Input Source to Inverter
Start the inverter by pressing the “inverter on” button on the front panel.
On the SSC hidden panel, press the “security” key and hold it while pressing the “forced bypass to inverter” key
(pushbutton #4). If enough modules are on, the load will be disconnected for 0.8 seconds, then connected to the
UPS modules.
2.11.3 Forced Transfer from Inverter to Bypass AC Input
On the UPS hidden panel, press the “security” key and hold it while pressing the “forced inverter to bypass” key
(pushbutton #5). The inverter will stop and disconnects the UPS modules. When all modules are stopped, the load
will be disconnected for 0.8 seconds; then connected to the bypass AC input source. See Figure 1-11.
IMPORTANT: When onr UPS module in a shared system is shut down, it
may cause the remaining modules to enter an overload or
current-limiting condition, if they are unable to fully support
the attached load. The remaining modules may shut down
after a certain time or immediately, (depending on the load
level), and the load may be transferred to the bypass AC
input source.
Operation
EPS 7000 Shared Systems
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