MI 2087 Instaltest 61557
Measurement instructions
19
Step 5
•
Press the
START
key and release it. Test voltage starts to rise (500 V/s) and as
soon as varistor’s forward current reaches the value of 1 mA (Breakdown
Voltage is defined at that current), the voltage will be displayed. Generator will
stop to generate test voltage.
•
Check the Breakdown voltage scaled to a.c. value called Uac pressing the
DISPLAY
key.
Meaning of the Uac voltage:
Protection devices intended for a.c. network are usually dimensioned approx. 20% of
nominal mains voltage above peak value of nominal mains voltage.
Example:
Nominal mains voltage Un = 230V
Upeak = 230V
⋅
1,41 = 324V
Ubreakdown = (Upeak + 0,2
⋅
Un)
≅
Un
⋅
1,6 = 368V
Uac voltage may be directly compared with the voltage declared on tested protection
device.
•
Store displayed result for documentation purpose; see instructions how to store
it in chapter 4.1. Storing of test results.
Notes!
•
In order test result not to be influenced by connected loads, tested Over-voltage
Protection Device must be removed from installation, before testing it.
•
If the Over-voltage Protection Device to be tested is not possible to be removed
from installation (permanent connection), make sure to disconnect all other
elements connected to installation, which may influence on test result.
bat
message, displayed during or after finishing the measurement means batteries
are too weak to guarantee correct result. Replace the batteries.
