11/ 2008
BENNING CM 9
11
as r.m.s. value. The measuring accuracy is specified for a sinusoidal
curve.
The stated precision is specified for conductors that are centrally clamped by the
current probe
1
(see Fig. 2 - 7). For conductors that are not centrally clamped,
an additional error of 1 % of the display value needs to be taken into account.
Filter damping characteristic - 24 db/ oct, filter limit frequency: 100 Hz
Influence of a magnetic field of parallel lines: 0.002 % typical value.
8. Making measurements with the BENNING CM 9
8.1 Preparations for making measurements
Operate and store the BENNING CM 9 only at the specified storage and opera-
ting temperatures conditions. Avoid continuous insulation.
- Strong sources of interference in the vicinity of the BENNING CM 9 can lead
to unstable readings and measuring errors.
- To simplify operation, the BENNING CM 9 is provided with an automatic
background lighting. As soon as the ambient lighting decreases, the back-
ground lighting of the current clamps will switch on.
8.2 Leakage current measurement
8.2.1 Leakage current measurement at the ground conductor
see figure 2:
leakage current measurement at the ground conductor
8.2.2 Differential current measurement at singlephase systems
see figure 3:
differential current measurement at single-phase systems
8.2.3 Leakage current measurement via ground conductor (charge
eliminator) for threephase supply
see figure 4:
leakage current measurement via ground conductor (charge
eliminator) for three-phase supply
8.2.4 Differential current measurement, load supplied in threephase,
without Ntype conductor
see figure 5:
differential current measurement, load supplied in three-phase,
without N-type conductor
8.2.5 Differential current measurement, load supplied in threephase,
with Ntype conductor
see figure 6:
differential current measurement, load supplied in three-phase,
with N-type conductor
8.2.6 Alternating current measurement
see figure 7:
alternating current measurement
9. Maintenance
Before opening the BENNING CM 9, make quite sure that it is
voltage free! Electrical danger!
9.1 Securing the instrument
Under certain circumstances safe operation of the BENNING CM 9 is no longer
ensured, for example in the case of:
- Visible damage of the casing.
- Incorrect measurement results.
- Recognizable consequences of prolonged storage under improper condi
-
tions.
- Recognizable consequences of extraordinary transportation stress.
In such cases the BENNING CM 9 must be switched off immediately, discon-
nected from the measuring points and secured to prevent further utilization.
9.2 Cleaning
Clean the casing externally with a clean dry cloth (exception: special cleaning
wipers). Avoid using solvents and/ or scouring agents for cleaning the instru-
ment. It is important to make sure that the battery compartment and battery
contacts are not contaminated by leaking electrolyte.
If electrolyte contamination or white deposits are present in the region of the
batteries or battery casing, clean them too with a dry cloth.
9.3 Battery change
Before opening the BENNING CM 9, make quite sure that it is
voltage free! Electrical danger!