Surge suppressor circuit board 1170-2 contains three varistors.
Which of them is correct for 240-250 volts power supply line:
NTE524V15 or NTE524V25 ?
Can anyone answer?
if you have just the L1 , L2 and Neutral connections from a transformer like this
you can use a NTE524V15 if its connected between L1 and Neutral or L2 and Neutral
you will need to use a NTE524V25 if its connected between L1 and L2
while you could trace the connections on the board but
a simple solution without the maintenance manual will be to measure the voltage across the varistor terminals on the board
if the voltage its about 120V use a NTE524V15
if the voltage its about 240V use a NTE524V25
John
PS
found this photo on line
its not clear what the 3 screw terminals are but I expect its going to be like this
PPS
if you connected the board to a 3 phase supply with 245 to 250V between phases
like this
you will need to use six NTE524V25
Last edited by john-100; 10-29-2018 at 12:13 PM.
Reason: add PPS