Testing Of 30 Ma Rcds; Testing Of Permanently Installed Rcds - Benning ST 725 Bedienungsanleitung

See figure 7b: T esting of three-phase appliances by means of active measuring adapters (test
object placed on insulated surface)
Note:
- The protective conductor current measurement is carried out using a current transformer
in the protective conductor of the measuring adapter (044140 or 044141) and by means of
the direct measurement method. The test object must be placed onto an insulated surface.
No part of the test object must have a connection to the earth potential. Otherwise, leakage
currents to earth might influence the measuring result.
- If it is not possible to place the test object onto an insulated surface, the protective conductor
current measurement can be carried out alternatively by means of the differential current
measurement method using the BENNING CM 9 leakage current clamp (044065). For this,
the test object must be put into operation by means of the optional measuring adapters
(044127 or 044128) and all active conductors (L1, L2, L3 and N) must be clamped by means
of the leakage current clamp. The BENNING CM 9 measures the protective conductor
current by means of the differential current measurement method.

9.5 Testing of 30 mA RCDs

The BENNING ST 725 allows measuring the tripping time of permanently installed RCDs and of
portable RCDs (PRCDs) with a nominal fault current of 30 mA. In the automatic test sequence,
the tripping time of the one-fold nominal fault current (initial polarity of 0°/ 180°) and of the five-
fold nominal fault current (initial polarity of 0°/ 180°) is measured.
By generating a fault current of 30 mA, it is proven that the RCD will trip when the nominal fault
current is reached. If the limiting value of the maximum contact voltage of 50 V is exceeded, the
"UB > 50 V" symbol will be shown on the display and the testing will be stopped.
Before testing an RCD, the 4 mm safety plug of the test cable must be
disconnected from the test socket 9 .
Measurement might be influenced by:
- a possibly existing voltage between the protective conductor of the

shockproof socket and earth
- leakage currents in the circuit behind the RCD
- further earthing equipment
- equipment which is connected behind the RCD and which will cause a
longer tripping time, e.g. capacitors or rotating machines
9.5.1

Testing of permanently installed RCDs

- Connect the IEC power cord to the IEC connector J of the BENNING ST 725.
- Connect the shock-proof plug to a shock-proof socket which is protected by the RCD to be
tested and switch on the RCD.
- Press the -key 6 to start the RCD test.
- If the "rESET" symbol is still shown on the display and the "LN" and "LE" symbols are
flashing, turn the shock-proof plug in the shock-proof socket by 180° and press the
6 again to start the test.
- Whenever the "rESEt" symbol appears on the display, switch the RCD on again.
- The BENNING ST 725 generates a fault current of 30 mA with positive (0°) or negative
(180°) initial polarity. The RCD trips and the tripping times of the one-fold nominal fault
current are measured.
- If the tripping time is less than the limiting value (200 ms), a
tripping time.
- Subsequently, the BENNING ST 725 generates a fault current of 150 mA with positive (0°) or
negative (180°) initial polarity. The RCD trips and the tripping times of the five-fold nominal
fault current are measured.
- If the tripping time is less than the limiting value (40 ms), a
tripping time.
- The test is considered to be passed, if "PASS" is shown on the display.
09/ 2014
BENNING ST 725
will be shown next to the
will be shown next to the

-key
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