I bought a size 2 motor starter on ebay. It is Allen Bradley and looks
like 500 series. (the label does not say what series).

I want to use it for my 10 HP compressor, which is the kind of service
where it would restart the motor many times per day.

Anyhow, I opened up the cover to look at contacts and it appears that
they have some wear. I cannot really tell if it is too much or not,
because I am not qualified to tell.

So, I have a couple of questions.

1) How can I know if the contacts are too worn?

2) If I buy an "aftermarket contact kit", are they really as good as
the originals? Do the original contacts have silver plates?

Thanks

i

"Ignoramus2083" wrote in message
...
I bought a size 2 motor starter on ebay. It is Allen Bradley and looks
like 500 series. (the label does not say what series).

I want to use it for my 10 HP compressor, which is the kind of service
where it would restart the motor many times per day.

Anyhow, I opened up the cover to look at contacts and it appears that
they have some wear. I cannot really tell if it is too much or not,
because I am not qualified to tell.

So, I have a couple of questions.

1) How can I know if the contacts are too worn?

2) If I buy an "aftermarket contact kit", are they really as good as
the originals? Do the original contacts have silver plates?

Thanks


You will see voltage drop and excessive temperature rise during use.

On Wed, 12 Oct 2011 14:17:18 -0500, Ignoramus2083
wrote:

I bought a size 2 motor starter on ebay. It is Allen Bradley and looks
like 500 series. (the label does not say what series).

I want to use it for my 10 HP compressor, which is the kind of service
where it would restart the motor many times per day.

Anyhow, I opened up the cover to look at contacts and it appears that
they have some wear. I cannot really tell if it is too much or not,
because I am not qualified to tell.

So, I have a couple of questions.

1) How can I know if the contacts are too worn?

2) If I buy an "aftermarket contact kit", are they really as good as
the originals? Do the original contacts have silver plates?

Thanks

i

Iggy, this is one of those good things to do on a new install. Even if
they aren't that bad. if you make it a policy to get your equipment in
top shape when you do work on it, you'll have way less downtime in the
future.

Karl

On 2011-10-12, Karl Townsend wrote:
On Wed, 12 Oct 2011 14:17:18 -0500, Ignoramus2083
wrote:

I bought a size 2 motor starter on ebay. It is Allen Bradley and looks
like 500 series. (the label does not say what series).

I want to use it for my 10 HP compressor, which is the kind of service
where it would restart the motor many times per day.

Anyhow, I opened up the cover to look at contacts and it appears that
they have some wear. I cannot really tell if it is too much or not,
because I am not qualified to tell.

So, I have a couple of questions.

1) How can I know if the contacts are too worn?

2) If I buy an "aftermarket contact kit", are they really as good as
the originals? Do the original contacts have silver plates?

Thanks

i

Iggy, this is one of those good things to do on a new install. Even if
they aren't that bad. if you make it a policy to get your equipment in
top shape when you do work on it, you'll have way less downtime in the
future.

Karl


Karl, I agree and I will do just that. But what do you think about
aftermarket contact kits? Are they OK?

i

On 2011-10-12, PrecisionmachinisT wrote:

"Ignoramus2083" wrote in message
...
I bought a size 2 motor starter on ebay. It is Allen Bradley and looks
like 500 series. (the label does not say what series).

I want to use it for my 10 HP compressor, which is the kind of service
where it would restart the motor many times per day.

Anyhow, I opened up the cover to look at contacts and it appears that
they have some wear. I cannot really tell if it is too much or not,
because I am not qualified to tell.

So, I have a couple of questions.

1) How can I know if the contacts are too worn?

2) If I buy an "aftermarket contact kit", are they really as good as
the originals? Do the original contacts have silver plates?

Thanks


You will see voltage drop and excessive temperature rise during use.



At 29 amps of FLA, a voltage drop of even 1 volt will melt the
contacts in short order. I do not think that voltage drop will be a
good indicator.

i

On Wed, 12 Oct 2011 19:53:27 -0500, Ignoramus2083
wrote:

On 2011-10-12, Karl Townsend wrote:
On Wed, 12 Oct 2011 14:17:18 -0500, Ignoramus2083
wrote:

I bought a size 2 motor starter on ebay. It is Allen Bradley and looks
like 500 series. (the label does not say what series).

I want to use it for my 10 HP compressor, which is the kind of service
where it would restart the motor many times per day.

Anyhow, I opened up the cover to look at contacts and it appears that
they have some wear. I cannot really tell if it is too much or not,
because I am not qualified to tell.

So, I have a couple of questions.

1) How can I know if the contacts are too worn?

2) If I buy an "aftermarket contact kit", are they really as good as
the originals? Do the original contacts have silver plates?

Thanks

i

Iggy, this is one of those good things to do on a new install. Even if
they aren't that bad. if you make it a policy to get your equipment in
top shape when you do work on it, you'll have way less downtime in the
future.

Karl


Karl, I agree and I will do just that. But what do you think about
aftermarket contact kits? Are they OK?

i

I'm sure they are fine

In article ,
Ignoramus2083 wrote:

At 29 amps of FLA, a voltage drop of even 1 volt will melt the
contacts in short order. I do not think that voltage drop will be a
good indicator.

Do the math, Mr. Algebra.com - any contact big enough to call itself a
motor starter will take 29 measly Watts all day long without melting
unless it's made of Wood's metal.

--
Cats, coffee, chocolate...vices to live by
Please don't feed the trolls. Killfile and ignore them so they will go away.

On 2011-10-13, Ecnerwal wrote:
In article ,
Ignoramus2083 wrote:

At 29 amps of FLA, a voltage drop of even 1 volt will melt the
contacts in short order. I do not think that voltage drop will be a
good indicator.

Do the math, Mr. Algebra.com - any contact big enough to call itself a
motor starter will take 29 measly Watts all day long without melting
unless it's made of Wood's metal.


I think that 29 watts per contact (three poles makes 87 watts) will
quickly destroy the contactor.

It may be helpful to go to ab.com and look in their literature library, it's
great to get instructions (for those who use instructions) on older
equipment.

We have an indexing festoon at work that cycles every few seconds 24/7, the
contactor welded itself closed, made a bit of a mess but out of 17 such
indexing festoons, we don't replace contactors very often. This was an AB
100 series IIRC.

RogerN



"Ignoramus2083" wrote in message
...

I bought a size 2 motor starter on ebay. It is Allen Bradley and looks
like 500 series. (the label does not say what series).

I want to use it for my 10 HP compressor, which is the kind of service
where it would restart the motor many times per day.

Anyhow, I opened up the cover to look at contacts and it appears that
they have some wear. I cannot really tell if it is too much or not,
because I am not qualified to tell.

So, I have a couple of questions.

1) How can I know if the contacts are too worn?

2) If I buy an "aftermarket contact kit", are they really as good as
the originals? Do the original contacts have silver plates?

Thanks

i

Ignoramus2083 wrote:
On 2011-10-13, lid wrote:
In ,
wrote:

At 29 amps of FLA, a voltage drop of even 1 volt will melt the
contacts in short order. I do not think that voltage drop will be a
good indicator.

Do the math, Mr. Algebra.com - any contact big enough to call itself a
motor starter will take 29 measly Watts all day long without melting
unless it's made of Wood's metal.


I think that 29 watts per contact (three poles makes 87 watts) will
quickly destroy the contactor.

I'm with Iggy on this one. No time to do the math,
but I have had experience trying to remove a couple
of watts of heat from a small semiconductor footprint.

Jim Stewart wrote:

I'm with Iggy on this one. No time to do the math,
but I have had experience trying to remove a couple
of watts of heat from a small semiconductor footprint.


Sigh. The contacts are a hell of a lot larger than the die in a
semiconductor, which may only be .001 square inch.


--
You can't have a sense of humor, if you have no sense.

"Michael A. Terrell" fired this volley in
m:

Sigh. The contacts are a hell of a lot larger than the die in a
semiconductor, which may only be .001 square inch.

They're also ignor(amus)ing (gotcha, Iggy) that the contacts are not just
floating alone in still air. They're welded or brazed to larger metal
pieces which form the armature or fixed contacts in the starter. Those
metal parts also dissipate heat (and conduct it away from the contacts
very well, by design).

Someone, probably a long time ago, kept the heat dissipation needs of
those parts in mind when they designed the contactor part of that
starter.

When it's working properly, I'd expect to see a larger drop across the
heaters than across the contacts.

LLoyd

Michael A. Terrell wrote:

Jim Stewart wrote:

I'm with Iggy on this one. No time to do the math,
but I have had experience trying to remove a couple
of watts of heat from a small semiconductor footprint.


Sigh. The contacts are a hell of a lot larger than the die in a
semiconductor, which may only be .001 square inch.

Sigh. By footprint I meant a TO-220 package.

Jim Stewart wrote:

Michael A. Terrell wrote:

Jim Stewart wrote:

I'm with Iggy on this one. No time to do the math,
but I have had experience trying to remove a couple
of watts of heat from a small semiconductor footprint.


Sigh. The contacts are a hell of a lot larger than the die in a
semiconductor, which may only be .001 square inch.

Sigh. By footprint I meant a TO-220 package.


The poackage is a lot larger than the die. It's the junction
temperature that's critical.


--
You can't have a sense of humor, if you have no sense.

"Lloyd E. Sponenburgh" wrote:

"Michael A. Terrell" fired this volley in
m:

Sigh. The contacts are a hell of a lot larger than the die in a
semiconductor, which may only be .001 square inch.

They're also ignor(amus)ing (gotcha, Iggy) that the contacts are not just
floating alone in still air. They're welded or brazed to larger metal
pieces which form the armature or fixed contacts in the starter. Those
metal parts also dissipate heat (and conduct it away from the contacts
very well, by design).

Someone, probably a long time ago, kept the heat dissipation needs of
those parts in mind when they designed the contactor part of that
starter.


Likely in Edison's day, when they had to manually adjust the field
current of their DC generators to maintain the proper output voltage.
there is little difference in very early designs and today's, other than
better insulation. Contactors I used in the '60s are almost identical
to today's. The older units were US made, but all bets are off for new
contactors.


When it's working properly, I'd expect to see a larger drop across the
heaters than across the contacts.


All he needs to do is check & log the temperature of the cabinet &
the contacts with a non contact IR thermometer once in a while. If he
notes any change in the differential, then it's time to either dress or
replace the contacts and retest.




--
You can't have a sense of humor, if you have no sense.

On Wed, 12 Oct 2011 14:17:18 -0500, Ignoramus2083
wrote:

I bought a size 2 motor starter on ebay. It is Allen Bradley and looks
like 500 series. (the label does not say what series).

I want to use it for my 10 HP compressor, which is the kind of service
where it would restart the motor many times per day.

Anyhow, I opened up the cover to look at contacts and it appears that
they have some wear. I cannot really tell if it is too much or not,
because I am not qualified to tell.

So, I have a couple of questions.

1) How can I know if the contacts are too worn?

Open up the contactor and look at the fixed and moving contacts,
then use your good judgment to assess them. Duh.

No, seriously. They are going to develop little pits and craters
from the arcing of normal operation, but they tend to self-correct as
they age (a bump on one side forms that fits into the crater of the
mating contact) until they totally run out of metal.

As long as they are overall flat, and the little button has a good
1/16" or so left, and they are all even with each other, you're good.

You can file the old set down to see what the actual contact area
is, but don't make a habit of it - you just kill them a lot faster.

The only time I really get crazy filing them is to get a totally bad
set working JUST long enough to run and get replacements. And they
have to start flat - because you swap the really bad contacts around
so at least one side has a little contact left. Bad moving set to two
halfway decent fixed points, and vice versa. Cross your fingers, and
get on your horse.

The real way to tell is to buy a replacement set of contacts -
that's the "before" that you want to remember how they look, and you
want it to still maintain the same basic profile allowing for a little
pitting.

You don't have to change the contacts now - just wrap the box up and
stash them - I'd put them *inside* the contactor enclosure, and when
it eventually fails on you... You open the box and see the 'present'
you left for yourself. Ten minutes later, you're good to go.

2) If I buy an "aftermarket contact kit", are they really as good as
the originals? Do the original contacts have silver plates?

The factory contacts are usually a Coin Silver alloy welded to a
plated Copper based bar or screw lug base. When the Silver runs out,
it'll start eating into the copper fairly fast - but they usually run
out of spring overtravel by then and the gap grows too large.

The replacements are supposed to be the exact same thing, because
there's often a UL Listing involved. But I would be really wary of
aftermarket ones made overseas, only because they might cheap out on
the contact buttons and they won't last nearly as long.

Heck, the replacements might be from the same factory that makes
them for the OEM, they just decided to sell direct too. But you have
no way to know. Caveat Emptor.

-- Bruce --

On Thu, 13 Oct 2011 02:41:52 -0500, "RogerN"
wrote:

It may be helpful to go to ab.com and look in their literature library, it's
great to get instructions (for those who use instructions) on older
equipment.

We have an indexing festoon at work that cycles every few seconds 24/7, the
contactor welded itself closed, made a bit of a mess but out of 17 such
indexing festoons, we don't replace contactors very often. This was an AB
100 series IIRC.

You've got a different problem - with that kind of short-cycling
service, the machines really should have been designed with a second
fail-safe contactor to kill incoming power to the whole machine if
this happens. Safety contactor, or a Shunt Trip Breaker.

The trick would be sensing the problem before the machine totally
crashes and self-destructs. Is there a hard stop or an indexing pin
at the station stop? Perhaps change it from a hard stop point (like
an adjustable bolt on a solenoid drop-pawl) to a really stiff spring
and the micro-switch to sense when it keeps pushing.

One other (far simpler) solution would be to change them out to an
electronic starter - Soft Start or a full on Variable Speed Drive.
Probably have to go way oversize on it because of the short-cycling
heating issues.

The VSD should have a sanity check built in that drops out the safety
contactor if the transistors(*) short - "Hey, I turned off but there's
still power on the Load. Something's Wrong Here..."

-- Bruce --

(* Transistors, SCR, SCS, Diac, Triac, etc. - whatever the hell they
used. There are several ways to do it.)

"Bruce L. Bergman (munged human readable)" wrote in message
...

On Thu, 13 Oct 2011 02:41:52 -0500, "RogerN"
wrote:

It may be helpful to go to ab.com and look in their literature library,
it's
great to get instructions (for those who use instructions) on older
equipment.

We have an indexing festoon at work that cycles every few seconds 24/7, the
contactor welded itself closed, made a bit of a mess but out of 17 such
indexing festoons, we don't replace contactors very often. This was an AB
100 series IIRC.

You've got a different problem - with that kind of short-cycling
service, the machines really should have been designed with a second
fail-safe contactor to kill incoming power to the whole machine if
this happens. Safety contactor, or a Shunt Trip Breaker.

The trick would be sensing the problem before the machine totally
crashes and self-destructs. Is there a hard stop or an indexing pin
at the station stop? Perhaps change it from a hard stop point (like
an adjustable bolt on a solenoid drop-pawl) to a really stiff spring
and the micro-switch to sense when it keeps pushing.

One other (far simpler) solution would be to change them out to an
electronic starter - Soft Start or a full on Variable Speed Drive.
Probably have to go way oversize on it because of the short-cycling
heating issues.

The VSD should have a sanity check built in that drops out the safety
contactor if the transistors(*) short - "Hey, I turned off but there's
still power on the Load. Something's Wrong Here..."

-- Bruce --

(* Transistors, SCR, SCS, Diac, Triac, etc. - whatever the hell they
used. There are several ways to do it.)



This uses a motor with brake and a prox switch to detect the index position.
I have a timer in the program that if it doesn't complete the index in time,
it alarms and shuts off the contactor, but that doesn't help when contacts
are stuck. I agree we should have a contactor that kills the 460V AC to the
starters when either the control detects a problem or when the E-Stop is
pressed. We do have a disconnect between the starter and motor so things
can be locked out.

I wouldn't have designed it the way it is but that's what the company has
used for years and hasn't had enough failures for them to decide to change
the circuit. Some of the new lines have VFD's for the festoon indexing, and
power is killed to the drives on E-Stop conditions.

RogerN