Chapter 1 Installation
14
MUST400_User manual_EN_REV02 User Manual
Protection against earth faults (RCD devices):
The RCD device installed upstream of the input supply should be comply with:
Sensitive to DC unidirectional pulses (class A) in the network
Insensitive to transient current pulses
Have an average sensitivity that is adjustable between 0.3A and 1A.
Fig.1- 3: The Symbols of RCCB
When using the RCD in the split bypass system or parallel system, the RCD should be installed upstream of
the input distribution to avoid wrong alarm.
The residual current introduced by RFI filter in the UPS is between 3.5mA and 1000mA. It is recommended to
confirm the sensitivity of each RCD of upstream input distribution and downstream distribution (to load).
1.5.2 External Battery
The DC compatible circuit breaker provides over current protection for UPS system and battery, which is
provided by the external battery cabinet.
1.5.3 UPS Output
In case of an external distribution cabinet is used for load distribution, the selection of protective
devices must provide discrimination with those that are used at the input to the UPS
(see Tab. 9-7).
