Adding Over Current protection to SCR Voltage Regulator Problem

Thread Starter

psoke0

Joined Mar 31, 2017
196
hello guys. i have a SCR voltage regulator that uses triac to drop mains voltage with a pot. i have added bridge rectifier to output so i can get DC .
and i have build a curcuit so that when im powering motor or a resistance when current is above about 10 amps its cuts the power and stays in that state.

here is the curcuit.

1705360906207.png




i have tested the curcuit without SCR regulator. and it does trip when reaching about 10 amps. but when i connect SCR its just keep tripping just about 1 amp. i have no idea why is it doing that. i tried everything that i know. im starting to loose it.
at first i thought that SCR gives high voltage at beggining and just trips the curcuit. so i run the curcuit without the protection with SW2 open. and SCR just powers the resistance just fine its heats up. and while its running i close the SW2 and its just trips it again at 2 amps of current draw. resistance is connected to relay Normally closed pin. when it reach about 10 amps it activates the relay to trip the curcuit. why could be the cause of this guys please help me out. thank you.
 

Pyrex

Joined Feb 16, 2022
263
hi,
it seems to me, filtering needed. The protection circuit operate OK with pure DC voltage only, not with pulsed voltage. Replace R8 to two resistors 510 Ohm each, connect them in series . Add 100uF capacitor from the connection point to the GND
 

Thread Starter

psoke0

Joined Mar 31, 2017
196
hi,
it seems to me, filtering needed. The protection circuit operate OK with pure DC voltage only, not with pulsed voltage. Replace R8 to two resistors 510 Ohm each, connect them in series . Add 100uF capacitor from the connection point to the GND
thank you for reply.
100 uF cap to which connection point ? between two 510 ohm resistor to ground or from shunt to ground
 
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