Fronius Symo Series Service Manual & Spare Parts List page 117

Only the leakage currents which occur at grid frequency may be used (50–60 Hz function
of the current injection probe). High frequency leakage currents distort the measurement
results *).
*) These requirements relate to DIN VDE 0701-0702 and ÖVE/ÖNORM E8701-1. In addi-
tion, individual national requirements and standards must also be observed.
Two processes may be used for measuring the ground conductor current:
- Direct process: Device must be insulated and may not be linked to another ground po-
tential.
- Differential current process:
Measurement can be carried out either at the inverter (loop outside the device) or in the
distributor. During the measurement in the distributor, ensure that no live conductors are
located in the immediate vicinity and no other consumers are on the same circuit.
Direct process – Measurement of the ground conductor current with the injection probe
via the PE conductor.
PE L1 N
mA
9 9
PE L1 N
1 Measuring instrument
2 Inverter
8 Insulated assembly of the object being tested
9 Measurement lead
Differential current process – Measurement of the ground conductor current using injec-
tion probe via N and L leads.
As with a residual circuit breaker, the currents are compared between the phase conductor
(L) and the neutral conductor (N) via a transformer. The difference is displayed.
PE L1 N
9 9 9
PE L1 N
1
9
Examples for measuring the ground conductor current
2
8
1 Measuring instrument
2 Inverter
9 Measuring lead
1
mA
2
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