Megger TORKEL 910, User Manual

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TORKEL 900-SERiES ZP-CS01E CS033663DE
6 EXTERNAL CURRENT MEASUREMENT
6
E
xternal current
measurement
6.1 General
External current measurement must be used when:
▪
TORKEL is working together with TXL Loads.
▪
Testing without disconnecting the regular load.
Since total current is measured, TORKEL can compensate
for changes attributable to the regular load. The total
current from the battery is then kept at a constant value.
This ensures accurate test results.
The external current measurement function enables
TORKEL to measure the total current in an external
path and base regulation on this measurement.
A DC clamp-on current probe (optional accessory) has
to be used for this measurement. it can be applied at
one of the battery terminals or at an inter-cell con-
nector. The DC clamp-on current probe must measure
the total current, including that which passes through
TORKEL.
A current shunt can also be used, but this requires
opening the current path and connecting the shunt
in series. The current shunt must be connected to the
negative side of the battery.
WARNING
External current shunt may not be used
above 300 V DC
Important
Always activate the warning and stop
limit functions when using external cur-
rent measurement. This will protect your
batteries if the DC clamp-on current probe
will malfunction.
Important
If a current shunt is used it must be con-
nected on the negative side of the bat-
tery.
Tip
For tests where it is important to obtain the
desired current within a few seconds or less it
is better to use internal current measurement
since it provides faster regulation.
6.2 Setting up external
current measurement
WARNING
See the chapter "2.2 Safety instructions"
on page 8.
DC clamp-on current probe
Preparation and requirements of the DC clamp-on
current probe to be used.
▪
The DC clamp-on current probe output voltage must not
exceed 1 V.
▪
Make sure that the DC clamp-on current probe has fresh
batteries. The batteries must last throughout the entire
test.
▪
The DC clamp-on current probe must be accurate and
calibrated and it must be able to carry a load of 600 k
Ω
.
Please note that a DC clamp-on current probe is usually
less accurate in the lowest part of its measurement range.
Resetting the output voltage
1]
Place the DC clamp-on current probe as far as
possible from any magnetic field
2]
Connect a DC voltmeter (set to 2 V full scale)
to the DC clamp-on current probe.
3]
Switch on the DC clamp-on current probe
and adjust its zero knob to set the output to
0.0 V
The mV/A ratio for the input can be set to a value
between 0.1 mV/A and 100 mV/A.
1]
In "TEST" press
2]
Press "Settings".