Manual

Gossen Metrawatt GmbH 43
12 Testing RCDs
The testing of residual current devices (RCDs) includes:
• Visual inspection
•Testing
• Measurement
Use the test instrument for testing and measurement.
Attention!
!
When testing systems with RCCBs, they may switch off.
This may occur even though it’s not normally provided
for by the test. Leakage currents may be present which,
in combination with the test current of the test instru-
ment, exceed the shutdown threshold value of the
RCCB. PCs which are operated in proximity to such
RCCB systems may switch off as a consequence. This
may result in inadvertent loss of data. Before conducting
the test, precautions should therefore be taken to ensure
that all data and programs are suitably backed up and
the computer should be switched off, if necessary. The
manufacturer of the test instrument assumes no liability
for any direct or indirect damage to equipment, comput-
ers, peripheral equipment or data bases when perform-
ing the tests.
Measuring Method
The following must be substantiated by generating a fault current
downstream from the RCD:
• That the RCD is tripped no later than upon reaching
its nominal fault current value
• That the continuously permissible touch voltage value
U
L
agreed upon for the respective system is not exceeded
This is achieved by means of:
• Touch voltage measurement
10 measurements with full-waves and extrapolation of I
N
• Substantiation of tripping within 400 ms or 200 ms with I
N
• Substantiation of tripping current with rising residual current
This value must be between 50% and 100% of I
N
(usually
about 70%).
• No premature tripping with the test instrument, because test-
ing is begun with 30% residual current (if no bias current
occurs within the system).
* only PROFITEST MTECH+, PROFITEST MXTRA
Test Standard
The following must be substantiated per IEC 60364-6:
– Touch voltage occurring at nominal residual current may not
exceed the maximum permissible value for the system.
– Tripping of the RCCB must occur within 400 ms (1000 ms for
selective RCDs) at nominal residual current.
Important Notes
• The test instrument permits simple measurements at all types
of RCDs. Select RCD, SRCD, PRCD etc.
• Measurement must be executed at one point only per RCD
(RCCB) within the connected electrical circuits. Low-resis-
tance continuity must be substantiated for the protective con-
ductor at all other connections within the electrical circuit (R
LO
or U
B
).
• The measuring instruments often display 0.1 V touch voltage
in TN systems due to low protective conductor resistance.
• Be aware of any bias currents within the system. These may
cause tripping of the RCDs during measurement of touch volt-
age U
B
, or may result in erroneous displays for measurements
with rising current:
Display = I
F
- I
bias current
• Selective RCDs identified with an can be used as the sole
means of protection for automatic shutdown if they adhere to
the same shutdown conditions as non-selective RCDs (i.e.
t
a
< 400 ms). This can be verified by measuring breaking time.
• Type B RCDs may not be connected in series with type A or F
RCDs.
Note
Bias Magnetization
Only AC measurements can be performed with the 2-
pole adapter. Suppression of RCD tripping by means of
bias magnetization with direct current is only possible via
a country-specific plug insert, e.g. SCHUKO, or the 3-
pole adapter.
I
N
3
-------
I
N
(measurement up to 1000 ms)
t
a
I
a
t
RCD/FI Table Waveform
Differential Current
Correct RCD/RCCB Function
Type AC Type A/F Type B*/
B+*
Type EV/
MI*
Alternating
current
Suddenly occurring
✔✔✔✔
Slowly rising
Pulsating
direct current
Suddenly occurring
✔✔✔
Slowly rising
Direct current
✔✔
Direct current
up to 6 mA
✔
S