Installation Liebert EXL S1
44
User Manual 10H52226UM60 - Rev. 1 - 01/2017
3.4. External protection devices
This device is equipped with manual switches intended only for Service Bypass and Internal Service
operations. It is therefore essential that the customer install external protection devices at the
installation site. These must be installed near the unit and labelled as the line power separation device
for the UPS (see IEC/EN 62040-1+A1:2013).
3.4.1. Use of differential protection devices
A differential device installed on the primary and bypass inputs supply senses the sum of all ground
leakage currents in both the UPS and the load it supplies.
To avoid spurious operation, the following must be taken into consideration when selecting
differential protection devices for installation on input lines:
1 The nominal value of ID must take into account the ground leakage current of the UPS and the
load under normal operating conditions: ID = ID
UPS
+ load leakage current.
N.B. The maximum limit for UPS ground leakage current is 5% of nominal input current (see IEC/
EN62040-1+A1:2013)
2 Be of a delayed operation type (greater than 30 0mS);
3 The type of differential switch used must conform to product regulation
IEC/EN62040-1+A1:2013.
Warning
The following label must be displayed on all switching devices installed in the same electrical
system as the UPS, even when they are located far from the area where the system is located
(according to European standard IEC/EN 62040-1+A1:2013):
MAKE SURE THE UNINTERRUPTIBLE POWER SYSTEM IS ISOLATED
BEFORE WORKING ON THIS CIRCUIT
Notice - Differential Current Breakers
• The UPS does not require differential protection devices connected ahead of it.
However, when these devices are installed in compliance with local regulations, note that
separate DCBs in the line power and bypass line power circuits may trip unexpectedly,
thus interrupting the power supply to the unit. Therefore, if a DCB must be installed, only
one should be used for both primary and bypass inputs.
• In parallel distributed systems, only one common differential protection device should be
installed ahead of the point where the line divides into the UPS primary and bypass line
power circuits. If separate DCBs are installed in different configurations, they may trip
unexpectedly.
• In order to guarantee correct distribution in the neutral cables, installation personnel
shall make sure that the lengths of the cables are as equal as possible.
However, if the bypass lines lead from sources that are electrically isolated from each
other, a differential protection device may be installed on each line.
In this case, and in cases when the load is supplied from the Bypass via the Static Bypass
Switch, the isolated sources are connected in parallel. A case-by-case analysis should be
made as to whether any resulting imbalance between the currents on the Bypass lines is
compatible with the respective protection devices.
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