Buzzing Relay

Thread Starter

imc

Joined Sep 13, 2022
7
Hi guys,

I've been putting together this control circuit for a railing actuator that needs to sync with a skylight opening and closing.
It's mocked up, and Relay 1 buzzes sometimes when the toggle is pushed to CLOSE, stops when Railing Down Limit switch is opened. It's a 120vac coil with 24vdc contacts. If Railing Down Limit is opened/closed repeatedly, the relay will sometimes buzz and sometimes not, so maybe a faulty relay?

This is really the first thing I've ever built with relays, so forgive me if I'm missing something obvious.

Thanks
Ian
 

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eetech00

Joined Jun 8, 2013
3,418
Hi guys,

I've been putting together this control circuit for a railing actuator that needs to sync with a skylight opening and closing.
It's mocked up, and Relay 1 buzzes sometimes when the toggle is pushed to CLOSE, stops when Railing Down Limit switch is opened. It's a 120vac coil with 24vdc contacts. If Railing Down Limit is opened/closed repeatedly, the relay will sometimes buzz and sometimes not, so maybe a faulty relay?

This is really the first thing I've ever built with relays, so forgive me if I'm missing something obvious.

Thanks
Ian
May we have a part number for the relay so we can check?
 

strantor

Joined Oct 3, 2010
6,112
Relay 1 has the coil in series with the skylight. It should not be that way. Probably the skylight is limiting current to the region where the relay just barely works.
 

Thread Starter

imc

Joined Sep 13, 2022
7
Relay 1 has the coil in series with the skylight. It should not be that way. Probably the skylight is limiting current to the region where the relay just barely works.
Oh, should have said - I'm just mocking up in the shop, so i've substituted in a lightbulb for the skylight motor. I realize that may present some problems down the road, as you point out, but for now it's out of the mix.
 

MaxHeadRoom

Joined Jul 18, 2013
25,977
This is really the first thing I've ever built with relays, so forgive me if I'm missing something obvious.
AC relays are fairly inefficient devices, if the voltage is slightly low or there is anything that stops the armature from closing tight, they buzz and draw extra current.
DC versions do not suffer from this and are on the whole, more efficient.
The latter are my preference.
 

Thread Starter

imc

Joined Sep 13, 2022
7
AC relays are fairly inefficient devices, if the voltage is slightly low or there is anything that stops the armature from closing tight, they buzz and draw extra current.
DC versions do not suffer from this and are on the whole, more efficient.
The latter are my preference.
How do I use the AC signal from my switch to control DC relays?
 

Thread Starter

imc

Joined Sep 13, 2022
7
As they are Chinese origin, they may be skimpy on the construction and no shading coil !
Required for AC relays.
Yeah, I'm starting to think that it's as simple as putting in a good quality part. Will let y'all know tomorrow if it works
 

Thread Starter

imc

Joined Sep 13, 2022
7
Relay 1 has the coil in series with the skylight. It should not be that way. Probably the skylight is limiting current to the region where the relay just barely works.
How would you recommend that I fix this? My first thought is to add a 4th relay after Closed Limit @ Skylight that will take the switching signal at it's coil and power the skylight through it's contacts?
 

strantor

Joined Oct 3, 2010
6,112
Oh, should have said - I'm just mocking up in the shop, so i've substituted in a lightbulb for the skylight motor. I realize that may present some problems down the road, as you point out, but for now it's out of the mix.
It doesn't matter whether it's a motor or a light bulb, you can't put anything in series with the relay coil. This is your problem and it won't be fixed by a more expensive relay.
 

strantor

Joined Oct 3, 2010
6,112
Sorry I realize this requires a significant redesign on your part as there's no longer any power to the other side of the skylight but there's no avoiding it:
20220913_183137.jpg
20220913_183408.jpg
 

strantor

Joined Oct 3, 2010
6,112
Sorry for talking over you, I just saw this
How would you recommend that I fix this? My first thought is to add a 4th relay after Closed Limit @ Skylight that will take the switching signal at it's coil and power the skylight through it's contacts?
I would change relays 1 & 2 to DPDT and run a wire parallel to the existing one. Like this;
20220913_190433.jpg
 
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