MI 3152(H)
Eurotest
XC (2,5 kV)
Tests and measurements
98
Measurement procedure
Enter the
Varistor test
function.
Set test parameters / limits.
Connect test cable to the instrument.
Connect test leads to object under test (see
Different test cable must be used for testing with MI 3152 where end voltage is 1000 V
and MI 3152H where end voltage is 2500 V. Also different test terminals are used.
The standard 3-wire test lead, Plug test cable or Plug / Tip commander can be used for
the Varistor test with end voltage 1000 V. For the 2500 V Varistor test the two wire 2.5
kV test lead should be used.
Start the measurement.
A voltage ramp starts from 50 V and rises with a slope of 100 V/s (Range parameter set
to 1000 V) or 350 V/s (Range parameter set to 2500 V). The measurement ends when
the defined end voltage is reached or if the test current exceeds the value of 1 mA.
After the measurement is finished wait until tested item is fully discharged.
Save results (optional).
Figure 7.17: Examples of varistor test result
Measurement results / sub-results
Uac
Calculated a.c. breakdown voltage
Udc
Breakdown voltage
Meaning of the Uac voltage
Protection devices intended for a.c. network are usually dimensioned approx. 15 % above peak
value of the nominal mains voltage. The relation between Udc and Uac is following:
𝑈𝑎𝑐 ≈
𝑈𝑑𝑐
1.15 × √2
Uac voltage may be directly compared with the voltage declared on tested protection
device.
