Humming relay question

In article <[email protected]>,
Brett A. Thomas <[email protected]> wrote:
>Allyn Vaughn wrote:
>> What is the current draw for the solenoid coil? Could it be that your
>> wire size (#26?) is too small to hold the current and that you are
>> possibly experiencing too much voltage drop to hold the coil?
>>
>> Just a thought.
>
>Thanks for the thought. I'm running 20 gauge wire, and, for my test
>setup, my single estop switch is about three feet away.
>
>Also, to be clear, the coil seems to be *holding*, it just hums while
>it's doing so and I want to make sure it's OK that it does so (and/or
>learn if there's some way to make it not hum that I don't know).

It _may_ be relatively 'mormal' for that relay.

Converting to _DC_ power (a whole $10, or so) could make for a signficant
noise reduction. NOTE: 'AC' coil relays _will_ work just fine on DC
power (the 'other way around' can be problematic :)

visit your neighborhood Radio Shack.

Look for a "bridge rectifier", rated for "at least" 24V -- 50V ones are
fairly common -- at a couple of amps.

Also a capacitor. rated at _at_least_ 50V, and at least 200 microfarad ("uf").

The bridge rectifier should be a 'little black box', with a lead at each
corner. one will be marked "+", the one opposite it will be marked "-",
and the other two will either be not labelled, or will have a sort-of "~".
Those last two are the AC input, connect one to each wire from the
transformer.

Connect the capacitor across the other two leads. making sure that the
"+" side of the capaitor is connected to the "+" output from the rectifier,
and "-" to "-". Then run connect the existing wiring to the switch/relay
to the "+" and "-", as well.

George wrote:
> If you're supplying constant hold-down voltage - the way you wired it - it
> will hum.
>
> Had I wired it, I would have had the safety switch control my pull - down
> current (NO) to a spring-loaded solenoid which would break the current to
> the shop. This would allow multiple paralleled panic switches, but would
> require a reset after a panic stop.

Yes, that makes sense. Thank you, that was very helpful.

-BAT

Robatoy wrote:
> Humming relay question...
>
> When I first saw the title... I had visions of 4 people, around a track,
> each running then humming a verse into the ear of the next guy...and so
> on...
> But I resisted expressing that vision in public.

You didn't resist it very well. :) But thanks for your suggestion.

-BAT

"Brett A. Thomas" wrote:

<snip>

> But, one question - the contactor hums. LOUDLY. It's only when the 24V
> is on; I can turn off the safety switch, but not hit an estop switch,
> and it'll hum. Is it supposed to do that?
>
> Brett

The output of a doorbell transformed is 24V A.C.. Is the relay designed for 24V A.C. or 24V D.C.?

--
Jack Novak
Buffalo, NY - USA
(Remove "SPAM" from email address to reply)

"Brett A. Thomas" <[email protected]> wrote in message
news:[email protected]...
>>
> But, one question - the contactor hums. LOUDLY. It's only when the 24V
> is on; I can turn off the safety switch, but not hit an estop switch,
> and it'll hum. Is it supposed to do that?
>

The way you have it wired, yes.

George wrote:
> "Brett A. Thomas" <[email protected]> wrote in message
> news:[email protected]...
>
>>But, one question - the contactor hums. LOUDLY. It's only when the 24V
>>is on; I can turn off the safety switch, but not hit an estop switch,
>>and it'll hum. Is it supposed to do that?
>>
>
>
> The way you have it wired, yes.

You could have chosen to be helpful.

Which begs the question: why are you here in the
first place? Is it to take what you can get and
give nothing? Or are you simply a troll?

Brett A. Thomas wrote:
> WoofWoof wrote:
>
>> George wrote:
>>
>>> The way you have it wired, yes.
>>
>> You could have chosen to be helpful.
>
>
> It had ocurred to me that I could get a switch which would control both
> the relay and the transformer, and cut power to both at the same time.
> Perhaps that's what he's talking about.

Perhaps it was. My point though was that, from his
statement, he either knows why this is happening
or believes he does and he could have supplied
that information for you and other interested
parties (like me). He chose not to contribute so
you have to wonder why he participated at all.

I thought at first he was a simple troll but he
actually seems quite a helful guy in other current
threads here.

"WoofWoof" <[email protected]> wrote in message
news:[email protected]...
> George wrote:
> > "Brett A. Thomas" <[email protected]> wrote in message
> > news:[email protected]...
> >
> >>But, one question - the contactor hums. LOUDLY. It's only when the 24V
> >>is on; I can turn off the safety switch, but not hit an estop switch,
> >>and it'll hum. Is it supposed to do that?
> >>
> >
> >
> > The way you have it wired, yes.
>
> You could have chosen to be helpful.
>
> Which begs the question: why are you here in the
> first place? Is it to take what you can get and
> give nothing? Or are you simply a troll?
>

As helpful as you?

http://www.detroitcoil.com/PAGES/How%20A%20DC%20Solenoid%20Works1.pdf In
case you're not just the dog fart you sign yourself.

"Brett A. Thomas" <[email protected]> wrote in message
news:[email protected]...
> WoofWoof wrote:
> > George wrote:
> >> The way you have it wired, yes.
> > You could have chosen to be helpful.
>
> It had ocurred to me that I could get a switch which would control both
> the relay and the transformer, and cut power to both at the same time.
> Perhaps that's what he's talking about. However, the relay humming
> while I'm not around isn't much of a concern to me. It's distracting
> while I am there, but I can learn to live with it, if it's inevitable.
>
> I'm more wondering whether the relay *should* be making that noise, if
> they all do that, or if mine's doing it because it's about to burst into
> flames, or something.
>
> I was at least smart enough not to wire the transformer off of subpanel
> B :)

If you're supplying constant hold-down voltage - the way you wired it - it
will hum.

Had I wired it, I would have had the safety switch control my pull - down
current (NO) to a spring-loaded solenoid which would break the current to
the shop. This would allow multiple paralleled panic switches, but would
require a reset after a panic stop.

George wrote:
> "WoofWoof" <[email protected]> wrote in message
> news:[email protected]...
>
>>George wrote:
>>
>>>"Brett A. Thomas" <[email protected]> wrote in message
>>>news:[email protected]...
>>>
>>>
>>>>But, one question - the contactor hums. LOUDLY. It's only when the 24V
>>>>is on; I can turn off the safety switch, but not hit an estop switch,
>>>>and it'll hum. Is it supposed to do that?
>>>>
>>>
>>>
>>>The way you have it wired, yes.
>>
>>You could have chosen to be helpful.
>>
>>Which begs the question: why are you here in the
>>first place? Is it to take what you can get and
>>give nothing? Or are you simply a troll?
>>
>
>
> As helpful as you?

I wasn't helpful to him because I didn't know the
answer to his question (I was as interested as he
to learn). You, on the other hand, did know but
chose not to help initially.

I'll leave it to others to judge which is worse.

> http://www.detroitcoil.com/PAGES/How%20A%20DC%20Solenoid%20Works1.pdf In
> case you're not just the dog fart you sign yourself.

As always, I think that kind of name-calling says
more about you than me ... but again, others can
judge. But anyway: *plonk*

"Brett A. Thomas" <[email protected]> wrote in message
news:[email protected]...
> George wrote:
> > If you're supplying constant hold-down voltage - the way you wired it -
it
> > will hum.
> >
> > Had I wired it, I would have had the safety switch control my pull -
down
> > current (NO) to a spring-loaded solenoid which would break the current
to
> > the shop. This would allow multiple paralleled panic switches, but
would
> > require a reset after a panic stop.
>
> Yes, that makes sense. Thank you, that was very helpful.
>

Sorry I simply answered your question the first time. I'm prone to do that.
Some give elaborate answers to their own questions instead, some just blast
in with ad-hominem accusations, for reasons unknown.

Can't take credit for the solution. It's the way every wood shop I've ever
worked in is wired.

"Brett A. Thomas" <[email protected]> wrote in message
news:[email protected]...
> George wrote:
> > Can't take credit for the solution. It's the way every wood shop I've
ever
> > worked in is wired.
>
> I think my complaint with it is that the failure mode is that, when you
> hit "stop," it wouldn't stop, since everything has to be intact in order
> to signal for a stop. But with what I have, the failure mode (an open
> in the wiring) is that nothing would work until it was fixed.
>
> The downside is the hum. But, if the hum isn't detrimental and doesn't
> signal something Bad Wrong (i.e., if the contactor is supposed to sound
> like that when it's engaged, and is designed to be engaged and hum for
> hundreds of hours at a time), then it's really no worse than the
> flourescents and I can live with it.
>
Get a different relay and a properly bridged DC power supply, then. You
know what you want. The emergency cut-off, obviously, assumes power is
present, else it wouldn't be used to cut it off.

Meant to include this.
http://www.detroitcoil.com/PAGES/What%20Is%20A%20Solenoid.pdf

And check the reply to the provocateur for DC.

"George" <george@least> wrote in message
news:[email protected]...
>
> >
> > The downside is the hum. But, if the hum isn't detrimental and doesn't
> > signal something Bad Wrong (i.e., if the contactor is supposed to sound
> > like that when it's engaged, and is designed to be engaged and hum for
> > hundreds of hours at a time), then it's really no worse than the
> > flourescents and I can live with it.
> >
> Get a different relay and a properly bridged DC power supply, then. You
> know what you want. The emergency cut-off, obviously, assumes power is
> present, else it wouldn't be used to cut it off.
>
>

"mac davis" <[email protected]> wrote in message
news:[email protected]...
> On Mon, 14 Feb 2005 10:33:30 -0500, Robatoy <[email protected]>
wrote:
>
> >
> >Humming relay question...
> >
> >When I first saw the title... I had visions of 4 people, around a track,
> >each running then humming a verse into the ear of the next guy...and so
> >on...
> >But I resisted expressing that vision in public.
>
> thank you for not sharing that.. *g*
>
I initially thought it had something to do with the Clinton Whitehouse....

Nova wrote:
> The output of a doorbell transformed is 24V A.C.. Is the relay designed for 24V A.C. or 24V D.C.?

The relay is a Cutler-Hammer C25DND330T. You can get formal specs here:

http://www.famousparts.com/c23pol30amp2.html

No idea if that seller is any good, they were the first Google hit that
had what I wanted. It's a 3 pole because that's all my local electrical
supply place had; I'm just not hooking up the third pole. It's listed
on that page as:

Coil Voltage Rating: 24 Volts AC

The doorbell tranformer is definitely 24 V AC output.

Everything's within spec - either this is normal for this setup
(George's opinion, I believe) or something's wrong. I suppose it's also
possible this setup is not just inadvisable, but Wrong.

-BAT

On Sun, 13 Feb 2005 22:05:00 -0800, "Brett A. Thomas" <[email protected]>
wrote:

>All,
>
>A while back I'd asked for advice on getting emergency stop switches
>going in the shop. Based on the advice from this group, I ordered these
>combo switches and normally closed contactor blocks, model E22JLB2N8B:
>
snip

What is the current draw for the solenoid coil? Could it be that your
wire size (#26?) is too small to hold the current and that you are
possibly experiencing too much voltage drop to hold the coil?

Just a thought.

Allyn

George wrote:
> Can't take credit for the solution. It's the way every wood shop I've ever
> worked in is wired.

I think my complaint with it is that the failure mode is that, when you
hit "stop," it wouldn't stop, since everything has to be intact in order
to signal for a stop. But with what I have, the failure mode (an open
in the wiring) is that nothing would work until it was fixed.

The downside is the hum. But, if the hum isn't detrimental and doesn't
signal something Bad Wrong (i.e., if the contactor is supposed to sound
like that when it's engaged, and is designed to be engaged and hum for
hundreds of hours at a time), then it's really no worse than the
flourescents and I can live with it.

-BAT

"WoofWoof" wrote in message

> As always, I think that kind of name-calling says
> more about you than me ... but again, others can
> judge. But anyway: *plonk*

Too bad, it will be your loss ... George and I aren't exactly enamored with
each other, but plonking him is the epitome of cutting off your nose to
spite your face, because you will learn something from his posts. So get
pissed if you must, we all do, but don't cut off your nose ....

... well, you get the picture.

--
www.e-woodshop.net
Last update: 11/06/04

Humming relay question...

When I first saw the title... I had visions of 4 people, around a track,
each running then humming a verse into the ear of the next guy...and so
on...
But I resisted expressing that vision in public.

In article <[email protected]>,
"Brett A. Thomas" <[email protected]> wrote:

[snipperectomy]

> But, one question - the contactor hums. LOUDLY. It's only when the 24V
> is on; I can turn off the safety switch, but not hit an estop switch,
> and it'll hum. Is it supposed to do that?
>

It could be something as simple as an AC vs DC issue.
Was the relay disigned for 24v AC?
That'd be the route I'd chase.
Then again....
*S*


0¿0

Rob.

"This guy was a mean killer.... he used a kitten as a silencer.."
(CSI)

On Mon, 14 Feb 2005 10:33:30 -0500, Robatoy <[email protected]> wrote:

>
>Humming relay question...
>
>When I first saw the title... I had visions of 4 people, around a track,
>each running then humming a verse into the ear of the next guy...and so
>on...
>But I resisted expressing that vision in public.

thank you for not sharing that.. *g*



mac

Please remove splinters before emailing

WoofWoof wrote:
> George wrote:
>> The way you have it wired, yes.
> You could have chosen to be helpful.

It had ocurred to me that I could get a switch which would control both
the relay and the transformer, and cut power to both at the same time.
Perhaps that's what he's talking about. However, the relay humming
while I'm not around isn't much of a concern to me. It's distracting
while I am there, but I can learn to live with it, if it's inevitable.

I'm more wondering whether the relay *should* be making that noise, if
they all do that, or if mine's doing it because it's about to burst into
flames, or something.

I was at least smart enough not to wire the transformer off of subpanel
B :)

-BAT

Allyn Vaughn wrote:
> What is the current draw for the solenoid coil? Could it be that your
> wire size (#26?) is too small to hold the current and that you are
> possibly experiencing too much voltage drop to hold the coil?
>
> Just a thought.

Thanks for the thought. I'm running 20 gauge wire, and, for my test
setup, my single estop switch is about three feet away.

Also, to be clear, the coil seems to be *holding*, it just hums while
it's doing so and I want to make sure it's OK that it does so (and/or
learn if there's some way to make it not hum that I don't know).

-BAT