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The Neutral Line
3.3.4.2.
Ac Input and Output connections
3.3.4.3.
INSTALLATION MUST BE PERFORMED BY A QUALIFIED TECHNICIAN ONLY!
Before connecting the main input and output cables to the UPS main terminals, verify that the
circuit breakers on the feed panel are in the OFF position.
Connect the rectifier ac input, bypass ac input, and ac output cables to the UPS.
UPS for 208 Vac Grid, Installation Guide, doc. rel. 3.0
When the UPS is operating, a neutral line must be connected at all times
and must not be disconnected at any time.
Caution: If at any time the neutral line becomes disconnected, there will
be no input or output reference voltage because the input neutral line and
the output neutral line are physically linked together. This may result in the
system defining its own reference voltage, which will be set by the load
distribution between the three phases.
This may cause damage to the load.
Caution: A 4-pole switching system can disconnect the neutral line.
Warning: If you have a four-pole mains-to-generator switching system,
you are in danger of having the neutral line disconnected when the four-
pole switch is operated. This can result in the problems described above.
To avoid these problems, it is strongly recommended that if you use a four-
pole mains-to-generator switching system, you install an isolation
transformer that constantly provides a neutral line to the UPS.
WARNING! RISK OF ELECTRICAL SHOCK OR INJURY!
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