G
AMATRONIC
E
LECTRONIC
I
NDUSTRIES
L
TD
.
Power+ PREMIUM, Installation Guide, rel.
1.7
45
Based on the principles explained above, in order to protect the UPS's bypass contactor and also the main
input of the UPS, for all scenarios including short circuit, Gamatronic recommends the following:
•
The circuit breaker that feeds the bypass input line and the circuit breaker feeding the main input of
UPS shall have no magnetic protection delay, or a maximum magnetic protection delay of 50 msec.
This ensures that the circuit breaker will interrupt the short circuit before any damage can be done to
the static switch contactor and the UPS modules.
If you choose to use a time-delay circuit
breaker on the bypass input line, recommended rating of the breaker is approximately
6 x “EE”; that is, 6 times the maximum bypass input current.
•
When using a circuit breaker with delayed magnetic protection, the ability of the cables and the rest
of the infrastructure to withstand a short circuit must be taken in account.
See Figure 7 and Figure 8 for suggested ratings of the main input switch and circuit breakers.
Ratings of circuit breakers and cables connected to the UPS must comply with applicable local and national
electrical codes at the installation site.
