Atlas Copco QAS 60 Pd, Instruction Manual

Page: 99 / 142

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9.3.12 IT-relay
The generator is wired for an IT network i.e. no
supply lines of the power supply are directly earthed.
A failure in insulation resulting in a too low insulation
resistance, is detected by the insulation monitoring
relay.
Q1 .......Circuit breaker for X1
Interrupts the power supply X1 when a
short-circuit occurs at the load side, or when
the overcurrent protection is activated.
When activated, Q1 interrupts the three
phases towards X1. It must be reset
manually after eliminating the problem.
Position O will only be used in
conjunction with an external earth
fault protection unit (e.g. integrated
in a distribution board).
If S13 is in position O, proper
earthing is of the utmost importance
for the safety of the user.
Eliminating any earth fault
protection can lead to serious injury
or even death for anybody touching
the unit or the load.
!
The generator shall not be operated
with other networks (such as TT or
TN). Doing so will cause tripping of
the insulation monitoring relay.
The generator is wired for an IT
network i.e. no supply lines of the
power supply are directly earthed.
A failure in insulation resulting in
too low an insulation resistance, is
detected by the insulation
monitoring relay.
At each start-up and any time a new
load is connected, the insulation
resistance must be verified. Check
for the correct setting of the
insulation monitoring relay (factory
set at 13 k
Ω ).
!
X1
Q1
N13
N14
S13