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22nd November 2019, 06:43 #1
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Issue with relay and snubber
This is the snubber circuit which I used to run an 230VAC induction motor.
Input 230VAC is given to RL1-3(COMMON point of RELAY).But when we check the voltage in RL1-2(NO in Relay),Input voltage appears at this point also,even the relay in OFF condition.
Due to this,the motor is started to run even the relay in OFF condition.
How to solve this issue..?
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22nd November 2019, 07:49 #2
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Re: Issue with relay and snubber
Hi,
Due to this,the motor is started to run even the relay in OFF condition.
Due to the capacitive impedance the current is limited to 34mA. If the motor and the load is that low power to make the motor move, then the snubber is designed too low impedance.
But I doubt the motor runs. As soon as you connect the motor the voltage will drop to a very small value.
--> It makes no sense to measure voltage on an high impedance node when no load is connected.
This is no real condition. Always measure voltage with real conditions.
KlausPlease donīt contact me via PM, because there is no time to respond to them. No friend requests. Thank you.
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22nd November 2019, 09:31 #3
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Re: Issue with relay and snubber
I tried it with real condition.
And if the relay is switched on and switched off means,the arc is forming between the contacts of relay.I used transparent relay to observe arc formation.
After switch off the relay also the load is running.Motor consuming 2.3A current..
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22nd November 2019, 09:35 #4
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Re: Issue with relay and snubber
Hi,
then exactly show how you connected mains and motor. We donīt see this now.
Itīs impossble to run more than 40mA via the capacitor... no way for 2.3A.
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22nd November 2019, 14:19 #5
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Re: Issue with relay and snubber
Itīs impossble to run more than 40mA via the capacitor... no way for 2.3A.
If your motor is taking about 2A current (say around 500W power or so) you should use a proper contactor OR a solid state relay.
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22nd November 2019, 23:17 #6
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Re: Issue with relay and snubber
Hi,
I strongly suspect that the capacitor is defective (failed due to high voltage spikes from the motor).
There still is the resistor that can't carry that 2.3A.
There is some systematic error, schematic error, measurement error....
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22nd November 2019, 23:17 #7
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Re: Issue with relay and snubber
did the resistor burn up? if not - your wiring is wrong ...
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23rd November 2019, 07:44 #8
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23rd November 2019, 08:43 #9
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Re: Issue with relay and snubber
Hi,
Impossible.
Please show a photo where we can see the wiring as well as the component values.
KlausPlease donīt contact me via PM, because there is no time to respond to them. No friend requests. Thank you.
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23rd November 2019, 10:08 #10
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Re: Issue with relay and snubber
There still is the resistor that can't carry that 2.3A.
Of course you are right. Something is fishy.
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23rd November 2019, 19:44 #11
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Re: Issue with relay and snubber
Hi,
I would suggest you check for continuity of the relay terminals to determine the NO, C and NC terminals of the relay. It seems to me like you have mistaken NC for NO.-------------
--Akanimo.
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23rd November 2019, 20:48 #12
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Re: Issue with relay and snubber
or else a faulty relay ...
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25th November 2019, 11:33 #13
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25th November 2019, 11:43 #14
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Re: Issue with relay and snubber
Hi,
maybe chattering relay?
maybe snubber values donīt fit to the motor?
maybe a wire wound resistor in the snubber circuit?
Maybe the snubber is at NC contact while the motor is at the NO contact (or vice versa)?
--> Try a varistor/MOV in parallel to the snubber.
KlausPlease donīt contact me via PM, because there is no time to respond to them. No friend requests. Thank you.
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25th November 2019, 13:17 #15
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25th November 2019, 13:36 #16
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Re: Issue with relay and snubber
You're probably expecting too much. Snubber or varistor won't eliminate contact arcing completely, just reduce it.
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25th November 2019, 13:50 #17
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25th November 2019, 15:48 #18
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Re: Issue with relay and snubber
What resistor and capacitor values are you using?
-------------
--Akanimo.
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25th November 2019, 22:22 #19
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25th November 2019, 22:50 #20
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Re: Issue with relay and snubber
G2R relays type is mentioned in the schematic, also fitting the photo. 10A 250VAC, suited for inductive load like motor.
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