Chauvin Arnoux C.A 6115N, User Manual

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5.9 Measuring resistance / testing continuity
This function enables resistance measurement up to 1999
Ω
, with DC voltage and automatic polarity
inversion. To take into account the resistance of the leads, it is possible to compensate for their resistance.
Additionally, a maximum resistance threshold can be programmed, with an audible signal to confirm the
measurement.
5.9.1 Description of the function
A measurement is first of all carried out to ensure that the voltage present is less than 3 V. If this
condition is met, the measurement begins. The battery is used as the voltage source. The DC voltage
and the current passing through the sample are measured, processed by the processor and displayed
as a resistance. By inverting the current flow, the second resistance R
2
is obtained.
To avoid voltage peaks at the switching relay due to the possible presence of inductance in the test
circuit, the inversion is only carried out once the measurement current has decreased.
For this reason the measurement time depends on the possible presence of inductance, it may amount
to several seconds if the inversion current is authorised.
It is possible to inhibit the automatic polarity inversion. Simply leave your finger on the TEST button. In
this case, the measurement is much quicker and gives out an audible signal of confirmation almost
instantaneously.
5.9.2 Technical specifications
Resistance (low impedance measurement) as per EN 61557-4 (Ed. 97) / DIN VDE 0413 part 4 (7/77)
Measurement range Resolution Accuracy
0.16 … 2.99 …19.90
Ω
... 1999
Ω
0.01 … 0.1 - 1
Ω
± (5 % of R. + 4 cts)
Internal resistance: Approx. 20
Ω
Measurement time: Approx. 5 s in the case of automatic polarity inversion, otherwise 1s
Permissible inductance: Max. 5 H without damage
Permissible parasite voltage in series:
≤
3 V AC / DC, measurement is not started beyond this value
Nominal voltage: 18 V DC
Short-circuit current:
≥
200 mA DC up to 10
Ω
, < 250 mA DC
Permissible overload: U
rms
max. = 500 V AC
Lead compensation: up to 5
Ω
max. (= R
∆
)
R
Indicated
= R
measured
- R
∆
5.9.3 Evaluation of measurements
The table below gives the maximum continuity values displayed, taking into account the measurement
error, so as to remain within the tolerated limits (see standards)
Theoretical resistances Maximum displayed resistances
0.2
Ω
0.15
Ω
0.4
Ω
0.35
Ω
0.6
Ω
0.54
Ω
0.8
Ω
0.73
Ω
1.0
Ω
0.92
Ω
10.0
Ω
9.47
Ω