Many years ago (possibly 50) you could buy a module that would take
the place of a starting relay or centrifugal cut-out for an AC motor.
Where do you find them? (I think I sent for one thru Popular Science
mag at the time)
Thanks

In article
,
Bob Villa wrote:

Many years ago (possibly 50) you could buy a module that would take
the place of a starting relay or centrifugal cut-out for an AC motor.
Where do you find them? (I think I sent for one thru Popular Science
mag at the time)
Thanks

I don't know about a solid state version. But, there are
electro-mechanical versions that are quite common on motors less than
1 hp. They control the input to the start winding with a current
sensitive relay. When the motor is turned on the inrush current closes
the circuit to the start winding. When the motor gets up to speed and
the current drops to the run value the relay opens the circuit the the
start winding. I believe Klixon made them. You might try and google them.

CP

I've seen 3-wire starters that were marked Solid State (triac, presumably),
as replacement parts for current-type start relays, typically for
refrigeration compressor motors (fractional HP).

Places like Johnstone, or other suppliers for HVAC service folks should have
numerous models to choose from.
You may need to know a motor's specs, at least the LRA locked rotor amps
rating, to be able to make an informed selection of starter devices.

The following is a post from rec.crafts.metalworking..

I bought a couple of used Dayton (1/3 HP) bench grinders recently, and found
some
Klixon current-type motor starter relays being used instead of centrifugal
switches for switching between Start and Run windings in these small
split-phase 120VAC induction motors.
http://www.sensata.com/klixon/motor-protector-3cr.htm

I mention these relays because they would be a suitable replacement for
damaged mechanical components or switch contacts related to centrifugal
switches.

These relays are the types used with refrigeration and air conditioning
compressors, and also completely suitable for other split-phase motors. They
have a heavy duty winding that the motor current passes thru, not a separate
coil like common relays.
When the power is turned on, the relay is pulled in, to make contact to the
Start winding.
The starting amperage of the motor is initially high, but it drops as the
rotor approaches Run speed, the relay drops out, connecting the line voltage
to the Run winding.

There are charts of different models of the SR start relays (in PDFs at the
link above), but I didn't find any type of selector guide for choosing what
the appropriate amp ratings would be for various HP ratings.
The models of Klixon SRs I was looking at were applicable for motors up to
15A (3CR series), and the next larger series of SRs were for up to 25A, so
these ratings would cover nearly all single phase split-phase motors
(capacitor start or non-capacitor start) used in a home shop environment.

One particular aspect of the SRs is that they are gravity-dependent, and
therefore need to be installed with the proper end pointed up.
Aside from that, they are highly reliable starting devices, rated for about
1 million cycles.

The specific ratings used for a 1/3 HP bench grinder motor use an 11A
pull-in (Start) spec and a 6A drop-out (Run) spec.
Of course, larger motors would use higher rated specs for pull-in and
drop-out currents, and the ratings vary in tenths-of-an-ampere (11.5A/6.3A,
etc).

--
Cheers,
WB
..............


"Bob Villa" wrote in message
...
Many years ago (possibly 50) you could buy a module that would take
the place of a starting relay or centrifugal cut-out for an AC motor.
Where do you find them? (I think I sent for one thru Popular Science
mag at the time)
Thanks

On Aug 21, 11:45*am, "Wild_Bill" wrote:
I've seen 3-wire starters that were marked Solid State (triac, presumably),
as replacement parts for current-type start relays, typically for
refrigeration compressor motors (fractional HP).

Places like Johnstone, or other suppliers for HVAC service folks should have
numerous models to choose from.
You may need to know a motor's specs, at least the LRA locked rotor amps
rating, to be able to make an informed selection of starter devices.

The following is a post from rec.crafts.metalworking..

I bought a couple of used Dayton (1/3 HP) bench grinders recently, and found
some
Klixon current-type motor starter relays being used instead of centrifugal
switches for switching between Start and Run windings in these small
split-phase 120VAC induction motors.http://www.sensata.com/klixon/motor-protector-3cr.htm

I mention these relays because they would be a suitable replacement for
damaged mechanical components or switch contacts related to centrifugal
switches.

These relays are the types used with refrigeration and air conditioning
compressors, and also completely suitable for other split-phase motors. They
have a heavy duty winding that the motor current passes thru, not a separate
coil like common relays.
When the power is turned on, the relay is pulled in, to make contact to the
Start winding.
The starting amperage of the motor is initially high, but it drops as the
rotor approaches Run speed, the relay drops out, connecting the line voltage
to the Run winding.

There are charts of different models of the SR start relays (in PDFs at the
link above), but I didn't find any type of selector guide for choosing what
the appropriate amp ratings would be for various HP ratings.
The models of Klixon SRs I was looking at were applicable for motors up to
15A (3CR series), and the next larger series of SRs were for up to 25A, so
these ratings would cover nearly all single phase split-phase motors
(capacitor start or non-capacitor start) used in a home shop environment.

One particular aspect of the SRs is that they are gravity-dependent, and
therefore need to be installed with the proper end pointed up.
Aside from that, they are highly reliable starting devices, rated for about
1 million cycles.

The specific ratings used for a 1/3 HP bench grinder motor use an 11A
pull-in (Start) spec and a 6A drop-out (Run) spec.
Of course, larger motors would use higher rated specs for pull-in and
drop-out currents, and the ratings vary in tenths-of-an-ampere (11.5A/6.3A,
etc).

--
Cheers,
WB
.............

"Bob Villa" wrote in message

...

Many years ago (possibly 50) you could buy a module that would take
the place of a starting relay or centrifugal cut-out for an AC motor.
Where do you find them? *(I think I sent for one thru Popular Science
mag at the time)
Thanks

This was a totally solid state device...like a timed triac that cuts-
out after a half second.

On Aug 20, 5:16*am, Bob Villa wrote:
Many years ago (possibly 50) you could buy a module that would take
the place of a starting relay or centrifugal cut-out for an AC motor.
Where do you find them? *(I think I sent for one thru Popular Science
mag at the time)
Thanks

It is amazing to me that they aren't commonly available!

On Mon, 23 Aug 2010 05:17:04 -0700, Bob Villa wrote:

On Aug 20, 5:16Â*am, Bob Villa wrote:
Many years ago (possibly 50) you could buy a module that would take the
place of a starting relay or centrifugal cut-out for an AC motor. Where
do you find them? Â*(I think I sent for one thru Popular Science mag at
the time)
Thanks

It is amazing to me that they aren't commonly available!



Google --- PLC module.

HTH

--
Live Fast, Die Young and Leave a Pretty Corpse

On Aug 23, 8:58*am, Meat Plow wrote:
On Mon, 23 Aug 2010 05:17:04 -0700, Bob Villa wrote:
On Aug 20, 5:16*am, Bob Villa wrote:
Many years ago (possibly 50) you could buy a module that would take the
place of a starting relay or centrifugal cut-out for an AC motor. Where
do you find them? *(I think I sent for one thru Popular Science mag at
the time)
Thanks

It is amazing to me that they aren't commonly available!

Google --- PLC module.

HTH

--
Live Fast, Die Young and Leave a Pretty Corpse

Not even close. This was a small (a little larger than a postage
stamp), simple device. I remember using one on a 5 HP motor that
wouldn't start. It was for a bakery mixing machine.

On Tue, 24 Aug 2010 06:28:50 -0700, Bob Villa wrote:

On Aug 23, 8:58Â*am, Meat Plow wrote:
On Mon, 23 Aug 2010 05:17:04 -0700, Bob Villa wrote:
On Aug 20, 5:16Â*am, Bob Villa wrote:
Many years ago (possibly 50) you could buy a module that would take
the place of a starting relay or centrifugal cut-out for an AC
motor. Where do you find them? Â*(I think I sent for one thru Popular
Science mag at the time)
Thanks

It is amazing to me that they aren't commonly available!

Google --- PLC module.

HTH

--
Live Fast, Die Young and Leave a Pretty Corpse

Not even close. This was a small (a little larger than a postage
stamp), simple device. I remember using one on a 5 HP motor that
wouldn't start. It was for a bakery mixing machine.

Thermistor across the start cap?



--
Live Fast, Die Young and Leave a Pretty Corpse

"Meat Plow" wrote in message
news
On Tue, 24 Aug 2010 06:28:50 -0700, Bob Villa wrote:

On Aug 23, 8:58 am, Meat Plow wrote:
On Mon, 23 Aug 2010 05:17:04 -0700, Bob Villa wrote:
On Aug 20, 5:16 am, Bob Villa wrote:
Many years ago (possibly 50) you could buy a module that would take
the place of a starting relay or centrifugal cut-out for an AC
motor. Where do you find them? (I think I sent for one thru Popular
Science mag at the time)
Thanks

It is amazing to me that they aren't commonly available!

Google --- PLC module.

HTH

--
Live Fast, Die Young and Leave a Pretty Corpse

Not even close. This was a small (a little larger than a postage
stamp), simple device. I remember using one on a 5 HP motor that
wouldn't start. It was for a bakery mixing machine.

Thermistor across the start cap?


Already suggested - he seems to be ignoring it.

Murata make a range of motor start thermistors (posistor).

By the look of the picture on the front of the catalogue they may be plug in
replacements for existing start winding solenoids.