Instructions

GMC-I Messtechnik GmbH 97
21.5 List of Abbreviations and their Meanings
RCCBs (residual current devices / RCDs)
I
Δ
Tripping current
I
ΔN
Nominal residual current
I
F
Rising test current (residual current)
PRCD Portable residual current device
PRCD-S:
with protective conductor detection and monitoring
PRCD-K:
with undervoltage trigger and protective conductor monitoring
RCD- Selective RCCB
R
E
Calculated earthing or earth electrode loop resistance
SRCD Socket residual current device (permanently installed)
t
a
Time to trip / breaking time
U
IΔ
Contact voltage at moment of tripping
U
IΔN
Contact voltage
relative to nominal residual current I
ΔN
U
L
Contact voltage limit value
Overcurrent Protective Devices
I
K
Calculated short-circuit current (at nominal voltage)
Z
L-N
Line impedance
Z
L-PE
Loop impedance
Earthing
R
B
Operational earth resistance
R
E
Measured earthing resistance
R
ELoop
Earth electrode loop resistance
Low-Value Resistance at
Protective, Earthing and Bonding Conductors
R
LO+
Bonding conductor resistance (+ pole to PE)
R
LO–
Bonding conductor resistance (– pole to PE)
Insulation
R
E(ISO)
Earth leakage resistance (DIN 51953)
R
INS
Insulation resistance
R
ST
Standing surface insulation resistance
Z
ST
Standing surface insulation impedance
Current
I
A
Breaking current
I
L
Leakage current (measured with current clamp trans-
former)
I
M
Measuring current
I
N
Nominal current
I
P
Test current
Voltage
f Line voltage frequency
f
N
Nominal voltage rated frequency
ΔU Voltage drop as %
U Voltage measured at the test probes during and after
insulation measurement R
INS
U
Batt
Battery voltage
U
E
Earth electrode voltage
U
INS
For measurement of R
INS
: test voltage, for ramp function:
triggering or breakdown voltage
U
L-L
Voltage between two phase conductors
U
L-N
Voltage between L and N
U
L-PE
Voltage between L and PE
U
N
Nominal line voltage
U
3~
Highest measured voltage during determination of
phase sequence
U
S-PE
Voltage between probe and PE
U
Y
Conductor voltage to earth
S