11.2.1 C-3 clamps
Clamps C-3 are used to measure AC in electrical systems of low and medium power. As op-tional
accessories for instruments produced by SONEL S.A., they are compatible with earth re-sistance me-
ters of MRU series and multifunctional meters of MPI series.
The output signal is conducted by a cable (1.5 m) ended with a pin adapted to the socket on the
meter.
NOTE!
Do not measure currents exceeding 1200 A. Limit the measurement time for currents
higher than 1000 A, according to the following data.
15 minutes of measure-
ment, followed by 30-
minute break
1)
For frequencies f 1 kHz. Limiting the maximum current in continuous operation for frequencies
above 1kHz according to the ratio:
Terms of reference
a) Temperature ................................................................................................................. +20…+26°C
b) Relative Humidity .............................................................................................................. 20…75%
c) Conductor .......................................................................................................... centred in the jaws
d) Frequency of sinusoidal current ........................................................................................48…65Hz
e) Total harmonic distortion .......................................................................................................... <1%
f) Current constant component ................................................................................................... none
g) Constant magnetic field .................................................................. <40A/m (Earth's magnetic field)
h) Variable, external magnetic field .............................................................................................. none
i) Conductors in the immediate vicinity ........................................................................ no current flow
Technical specifications
1)
as % of the measured value
a) output for maximum power .................................................................................................... 1A AC
b) ratio ...................................................................................................................................... 1000/1
c) frequency range.......................................................................................................... 30Hz...10kHz
Other data
a) type of insulation .......................................................................... double, according to EN 61010-1