Manual

48 Gossen Metrawatt GmbH
12.2.4 Testing of RCCBs
which are Suitable for Pulsating DC Residual Current
In this case, RCCBs can be tested with either positive or negative
half-waves. The standard calls for tripping at 1.4 times nominal
current.
Select Measuring Function
Set Parameter – Positive or Negative Half-Wave
Set Parameter – Test With and Without “No-Trip Test”
No-Trip Test
If, during the no-trip test which lasts for 1 sec-
ond, the RCD trips too early at 50% I
N
, i.e.
before the actual tripping test starts, the pop-up
window shown at the right appears.
Note
The following restrictions apply to the selection of tripping
current multiples relative to nominal current:
500 mA: double and five-fold nominal current is not pos-
sible in this case.
Note
According to DIN EN 50178 (VDE 160), only type B
RCCBs (AC-DC sensitive) can be used for equipment
with > 4 kVA, which is capable of generating smooth DC
residual current (e.g. frequency converters).
Tests with pulsating DC fault current only are not suitable
for these RCCBs. Testing must also be conducted with
smooth DC residual current in this case.
Note
Measurement is performed with positive and negative
half-waves for testing RCCBs during manufacturing. If a
circuit is charged with pulsating direct current, the func-
tion of the RCCB can be executed with this test in order
to assure that the RCCB is not saturated by the pulsating
direct current so that it no longer trips.
12.3 Testing of Special RCDs
12.3.1 Systems with Type RCD-S Selective RCCBs
Selective RCCBs are used in systems which include two series
connected RCCBs which are not tripped simultaneously in the
event of a fault. These selective RCCBs demonstrate delayed
response characteristics and are identified with the symbol.
Measuring Method
The same measuring method is used as for standard RCCBs (see
sections 12.1 on page 44 and 12.2.1 on page 46).
If selective RCDs are used, earthing resistance may not exceed
half of the value for standard RCCBs.
For this reason, the instrument displays twice the measured value
for touch voltage.
Select Measuring Function
Set Parameter – Selective
Start Measurement
Tripping Test
➭ Press the I
N
key. The RCCB is tripped. Blinking bars appear
at the display panel, after which time to trip t
A
and earthing re-
sistance R
E
are displayed.
The tripping test need
only be performed at
one measuring point for
each RCCB.
I
N
Neg. half-wave
Pos. half-wave
Negative direct current
Positive direct current
Waveform:
X times tripping current:
50% I
N
*
* No-trip test
with 50% I
N
S
I
N
I
F
or
Type 1: