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TGH1266E -
05/04
7 Practical Use
Use as a Portable
Insulation Fault
Location Device
Warning
The primary application of the EDS3065 is as a portable insulation fault location device in IT
systems, AC 19,2 ... 575 V and DC 19,2 ... 504 V.
After concluding considerations as to whether it is possible and/or sensible to search for insulation
faults, and about the technical measurement limits of the system, the actual fault location operation
may be started. The sequence of a search for insulation faults is described below, with the use of
examples.
•
Test the nominal system voltage: does this fall within the permissible limits for the
EDS3065?
•
Check whether the insulation fault reported by the insulation monitoring device can be
found. On this point, consult the chapter on POINTS TO BE CONSIDERED
BEFORE USE.
•
Before making a connection to the system which is to be checked, it is absolutely
essential to connect the green-yellow lead over the PE socket of the PGH185 insulation
fault test device with the PE of the system. It is advisable to connect up the test device
at the supply input (transformer or battery).
•
Connect the PGH185 insulation fault test device to the system which is to be checked,
using the two connection leads supplied with the device.
When you do this, you must
comply with the general guidelines for ‘live’ work.
In a three-phase (rotary) system: connect sockets L1, L2 and L3.
In a single-phase system, AC or DC: connect sockets L1 and L2.
•
Connect the insulation fault test device to the power supply, using the mains
connection cable supplied with the device. When you do this, note the level of the
supply voltage and compare it with the manufacturer’s nameplate. Do not connect a
supply voltage which is different from the one stated on the manufacturer’s nameplate!
•
If the insulation monitoring device which is present in the IT system has
an internal
ohmic resistance < 120 k
Ω
,
disconnect it from the system. When you do this,
disconnect all poles of the system coupling. It is not sufficient to switch off the supply
voltage to the insulation monitoring device.
•
Check the switch position I
max
on the PGH185. The factory setting is 25mA. If the IT
system contains components which might already operate at low currents, then it may
be necessary to select the 10 mA switch position. Note: the maximum test current
flows between the system and earth, not as a load current. Undesired operation is
therefore only possible if an insulation fault is combined with the test cycle.
•
Switch on the PGH185 insulation fault test device. The ON LED must light up, the
two test cycle LEDs must light up in time with the cycle and then go out again.
The test cycle corresponds to the illustration opposite, with a 2-second positive phase, a
4-second pause period and a 2-second negative phase. If the LEDs fail to show any
activity whatsoever, the supply voltage and the built-in 100 mA fine-wire fuse should be
checked.
