METREL EurotestCOMBO MI 3125 - Trip-Out Time (Rcdt)

MI 3125 / BT EurotestCOMBO Measurements
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RCD type
Contact voltage Uc
proportional to
Rated I
N
AC
1.05I
N
any
All models
AC
S
21.05I
N
A, F
1.41.05I
N
 30 mA
A, F
S
21.41.05I
N
A, F
21.05I
N
< 30 mA
A, F
S
221.05I
N
B, B+
21.05I
N
any
Model MI 3125 BT
B, B+
S
221.05I
N
Table 5.1: Relationship between Uc and I

N
Loop resistance is indicative and calculated from Uc result (without additional
proportional factors) according to:
N
C
L
I
U
R


.
Figure 5.18: Example of contact voltage measurement results
Displayed results:
Uc ........ Contact voltage.
Rl ......... Fault loop resistance.
5.4.2 Trip-out time (RCDt)
Trip-out time measurement verifies the sensitivity of the RCD at different residual
currents.
Trip-out time measurement procedure
* model MI 3125 BT
 Select the RCD function using the function selector switch.
 Set sub-function RCDt.
 Set test parameters (if necessary).
 Connect test cable to the instrument.
 Connect test leads to the item to be tested (see figure 5.17).
 Press the TEST key to perform the measurement.
 Store the result by pressing the MEM key (optional)*.