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HT33 Series User Manual
2.3.6 Cable Entry
A lower incoming line is used for 10KVA~30KVA UPS.
2.4 Protective Devices
For safety concerns, it is recommended to install external circuit breakers or other protective devices
for the input AC supply of the UPS system. This section provides generic practical information for
qualified installation engineers. The installation engineers should have the knowledge of the regulatory
wiring standards, and of the equipment to be installed.
2.4.1 Rectifier and Bypass Input Supply of the UPS
Install suitable protective devices in the distribution unit of the incoming mains supply, considering
the power cable current-carrying capacity and overload capacity of the system. Generally, the magnetic
circuit breaker with IEC60947-2 tripping curve C (normal) at the 125% of the current listed in table 2-1 is
recommended.
Note
For IT power network system, 4-pole protective device must be installed on the external input distribution of the
UPS.
Earth leakage current
If protection against earth faults (RCD devices) is required for the upstream of the input supply, the
installed device should:
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-1A
The RCCB must be sensitive to DC unidirectional pulses (class A) in the network, while insensitive
to transient current pulses, as shown in fig 2-3 respectively.
Fig 2-3 RCCB sign
2.4.2 Battery
A battery unit is composed of 40 batteries connected in series, a centreline is drawn from in between
(the joint part between the 20th and 21st battery), plus the line drawn from the front and back, there are
altogether 3 lines connected with UPS line contact bank. The battery line must push through a DC circuit
breaker before connecting to corresponding UPS line contact bank. The detailed wiring please refers to
fig 2-4 below:
