Gamatronic Electronic Industries Ltd.
POWER+ RM100,
3
X
208
V, User Guide, 1.3
29
7.2
The Power+ always requires a neutral line
During both installation and operation of the Power +, a neutral line must always be connected to the UPS.
This neutral line shall be connected during the entire period that the UPS is working, and shall 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. That may
result in system defining its own reference voltage, which will be set by the load distribution between the
three phases.
This can result in serious damage to the UPS.
7.2.1 A 4-pole switch might disconnect the neutral line
WARNING!
If you have a mains-to-generator
four-pole
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, we strongly recommend that, if you use a four-pole mains-to-generator switching
system, you install an isolation transformer that will constantly provide the UPS with a neutral line.
Figure 24 on page 31 illustrates the wrong way to connect the UPS with a grounded-neutral generator.
Figure 25 on page 32 illustrates an acceptable connection solution if you already have a grounded-neutral
generator.
Figure 26 on page 33 shows the preferred generator (neutralized, not grounded) and the preferred
connection (three-pole).
