I wast just browsing a DC thread where "magnetic switches" are
discussed. Not the first time I've seen the term, and I know what they
were talking about, but I DAGS and the first 40 or 50 hits mostly
related to burglar alarm type switches, and none referred to the "punch
red for off, punch green for on, don't power the tool up after a power
failure" type switch that makes sense for woodworking and other
machinery. Grizzly's web site lists them as magnetic switches, but a
search at Grainger's web site for "magnetic switch" returned alarm type
switches and relays, and at McMaster-Carr returned alarm switches. I
didn't keep searching very long, so I didn't find what I was looking for
at either site.
I guess what I'm getting around to is a question: Is there another name
for this type of switch?
They're very simple devices. The actual switch for power to the tool is
a relay. The relay's coil gets power either through a set of contacts
on the relay itself, or applied via a normally open momentary switch
(the "on" button). A normally closed momentary switch in series with
the coil power is the "off" switch.
A relay with a 110VAC coil and appropriately rated contacts, a NC
pushbutton (red for off) and a NO pushbutton (green for on) and an
appropriate enclosure are all you need to make one of these.
If one wanted a separate start/stop switch for the dust collector at
every tool, it would be easy for the electrically inclined woodworker to
build a switch that would support a remote start/stop pair for the DC at
every station. All of the start buttons would be in parallel, while all
of the stop buttons would be in series (this could be obnoxious if you
have a bad connection on the "stop" side). I'd probably use a 24VAC for
the control side, which would mean a 3 pole relay or an extra 24VAC
transformer.
There are also current sensing controls. Attach one of these devices to
a power wire on a tool (there is no electrical connection, it senses the
magnetic field caused by the current flowing through the wire) and use
it to apply power to the DCs relay. I couldn't find these right off,
either. anyone know what they're called?
just random thoughts and questions....
-j
Woodwork magazine recently had an article on making your own. The Grizz
switches work well, I use them in my shop.
--
Rumpty
Radial Arm Saw Forum: http://forums.delphiforums.com/woodbutcher/start
- - - - - - - - - - - - - - - - - - - - -
"Joe User" <[email protected]> wrote in message
news:[email protected]...
> I wast just browsing a DC thread where "magnetic switches" are
> discussed. Not the first time I've seen the term, and I know what they
> were talking about, but I DAGS and the first 40 or 50 hits mostly
> related to burglar alarm type switches, and none referred to the "punch
> red for off, punch green for on, don't power the tool up after a power
> failure" type switch that makes sense for woodworking and other
> machinery. Grizzly's web site lists them as magnetic switches, but a
> search at Grainger's web site for "magnetic switch" returned alarm type
> switches and relays, and at McMaster-Carr returned alarm switches. I
> didn't keep searching very long, so I didn't find what I was looking for
> at either site.
>
> I guess what I'm getting around to is a question: Is there another name
> for this type of switch?
>
> They're very simple devices. The actual switch for power to the tool is
> a relay. The relay's coil gets power either through a set of contacts
> on the relay itself, or applied via a normally open momentary switch
> (the "on" button). A normally closed momentary switch in series with
> the coil power is the "off" switch.
>
> A relay with a 110VAC coil and appropriately rated contacts, a NC
> pushbutton (red for off) and a NO pushbutton (green for on) and an
> appropriate enclosure are all you need to make one of these.
>
> If one wanted a separate start/stop switch for the dust collector at
> every tool, it would be easy for the electrically inclined woodworker to
> build a switch that would support a remote start/stop pair for the DC at
> every station. All of the start buttons would be in parallel, while all
> of the stop buttons would be in series (this could be obnoxious if you
> have a bad connection on the "stop" side). I'd probably use a 24VAC for
> the control side, which would mean a 3 pole relay or an extra 24VAC
> transformer.
>
> There are also current sensing controls. Attach one of these devices to
> a power wire on a tool (there is no electrical connection, it senses the
> magnetic field caused by the current flowing through the wire) and use
> it to apply power to the DCs relay. I couldn't find these right off,
> either. anyone know what they're called?
>
> just random thoughts and questions....
>
> -j
On Wed, 15 Jun 2005 09:43:58 -0500, the opaque Joe User
<[email protected]> spake:
>I wast just browsing a DC thread where "magnetic switches" are
>discussed. Not the first time I've seen the term, and I know what they
>were talking about, but I DAGS and the first 40 or 50 hits mostly
>related to burglar alarm type switches, and none referred to the "punch
>red for off, punch green for on, don't power the tool up after a power
>failure" type switch that makes sense for woodworking and other
>machinery. Grizzly's web site lists them as magnetic switches, but a
>search at Grainger's web site for "magnetic switch" returned alarm type
>switches and relays, and at McMaster-Carr returned alarm switches. I
>didn't keep searching very long, so I didn't find what I was looking for
>at either site.
>
>I guess what I'm getting around to is a question: Is there another name
>for this type of switch?
"Magnetic Starter Switch" was the old full name I learned.
-------------------------------------------
Crapsman tools are their own punishment
http://diversify.com Comprehensive Website Design
======================================================
Use a regular relay or contactor. Energize coil with 2 momentary
contact switches, one a normally open (Start) and the other a normally
closed (Stop), in series. One end of switches in series to AC hot
(Black wire) and other end of series switches to switched output of
relay or contactor. Add appropriate resistor in line to avoid burning
out coil in case it's not the voltage you're switching.
-- Teri
Make a search for "magnetic contactor" - that's the correct term for
switches used for most woodworking machines. Andy gave a pretty
comprehensive description. Motor starters are contactors for use when
the motors don't have integral overload devices. Starters combine a
contactor with an overload device and an incoming line disconnect
device (either a fused switch or circuit breaker).
Hope this helps,
John Sellers
"Joe User" <[email protected]> wrote in message
news:[email protected]...
> I wast just browsing a DC thread where "magnetic switches" are
> discussed. Not the first time I've seen the term, and I know what
they
> were talking about, but I DAGS and the first 40 or 50 hits mostly
> related to burglar alarm type switches, and none referred to the
"punch
> red for off, punch green for on, don't power the tool up after a
power
> failure" type switch that makes sense for woodworking and other
> machinery. Grizzly's web site lists them as magnetic switches, but a
> search at Grainger's web site for "magnetic switch" returned alarm
type
> switches and relays, and at McMaster-Carr returned alarm switches.
I
> didn't keep searching very long, so I didn't find what I was looking
for
> at either site.
>
> I guess what I'm getting around to is a question: Is there another
name
> for this type of switch?
>
> They're very simple devices. The actual switch for power to the
tool is
> a relay. The relay's coil gets power either through a set of
contacts
> on the relay itself, or applied via a normally open momentary
switch
> (the "on" button). A normally closed momentary switch in series
with
> the coil power is the "off" switch.
>
> A relay with a 110VAC coil and appropriately rated contacts, a NC
> pushbutton (red for off) and a NO pushbutton (green for on) and an
> appropriate enclosure are all you need to make one of these.
>
> If one wanted a separate start/stop switch for the dust collector at
> every tool, it would be easy for the electrically inclined
woodworker to
> build a switch that would support a remote start/stop pair for the
DC at
> every station. All of the start buttons would be in parallel, while
all
> of the stop buttons would be in series (this could be obnoxious if
you
> have a bad connection on the "stop" side). I'd probably use a 24VAC
for
> the control side, which would mean a 3 pole relay or an extra 24VAC
> transformer.
>
> There are also current sensing controls. Attach one of these devices
to
> a power wire on a tool (there is no electrical connection, it senses
the
> magnetic field caused by the current flowing through the wire) and
use
> it to apply power to the DCs relay. I couldn't find these right off,
> either. anyone know what they're called?
>
> just random thoughts and questions....
>
> -j
Andy Dingley wrote:
> Personally I only use the contactor sort. I've replaced the magnetic
> catch sort, except I think for just one left - and that's going when I
> get round to it.
Do you have a URL to a source of supply?
--
Mortimer Schnerd, RN
[email protected]
On Wed, 15 Jun 2005 09:43:58 -0500, Joe User <[email protected]> wrote:
>I guess what I'm getting around to is a question: Is there another name
>for this type of switch?
Lots. There are also two sorts of "magnetic switch" - one good, one
cheap.
Most of the names are generic though and apply equally to either sort of
switch. In the UK they're frequently called NVR switches (no-volt
release, because they automatically turn off if the power fails, so the
machine can't start unexpectedly if the power comes back).
You may also hear them called "starters". These are inaccurate shorthand
for "motor starters", aka "star-delta switches", a complex time-switch
used for 3-phase motors. They start the motor in high-torque mode, then
re-arrange the supply to the three windings for more efficient running.
The good ones are "contactors" (actually the contactor is just one
component inside) These are electrically activated switches, moved
entirely by an electromagnet's field. They're controlled by two small
low current pushbuttons, which may be mounted remotely.
The bad ones are usually called "magnetic switches". The contact is made
by pressing the on button, and held in place by a mechanical latch
(just like a non-magnetic switch). However this latch relies on a
magnetic solenoid too, hence the name and their no-volt release
behaviour. They have several drawbacks:
- They're often cheaply made. They can tend to switch off owing to
machine vibration.
- You can only have one "on" button, and it's mounted directly on the
switch. You can't remote control them.
- Their NVR behaviour isn't reliable. They're not permitted for many
industrial machines acccording to UK HSE rules.
- Although it's theoretically possible, you usually can't access the
connection need to add further "off" buttons. With a real contactor you
can easily add knee or pedal E-stop switches to a machine.
Either type can also have over-load windings added to protect the motor.
Personally I only use the contactor sort. I've replaced the magnetic
catch sort, except I think for just one left - and that's going when I
get round to it.
--
Cats have nine lives, which is why they rarely post to Usenet.
In article <[email protected]>,
Larry Jaques <novalidaddress@di\/ersify.com> wrote:
>On Wed, 15 Jun 2005 09:43:58 -0500, the opaque Joe User
><[email protected]> spake:
>
>>I wast just browsing a DC thread where "magnetic switches" are
>>discussed. Not the first time I've seen the term, and I know what they
>>were talking about, but I DAGS and the first 40 or 50 hits mostly
>>related to burglar alarm type switches, and none referred to the "punch
>>red for off, punch green for on, don't power the tool up after a power
>>failure" type switch that makes sense for woodworking and other
>>machinery. Grizzly's web site lists them as magnetic switches, but a
>>search at Grainger's web site for "magnetic switch" returned alarm type
>>switches and relays, and at McMaster-Carr returned alarm switches. I
>>didn't keep searching very long, so I didn't find what I was looking for
>>at either site.
>>
>>I guess what I'm getting around to is a question: Is there another name
>>for this type of switch?
>
>"Magnetic Starter Switch" was the old full name I learned.
I learned it was called a "locked out relay".
"Roy Smith" <[email protected]> wrote in message
news:[email protected]...
> I learned it was called a "locked out relay".
Could that have been "latching relay"? That's what they consist of.
On Wed, 15 Jun 2005 18:12:10 GMT, "Mortimer Schnerd, RN"
<[email protected]> wrote:
>Do you have a URL to a source of supply?
No - I buy mine by walking into a local shop. I'm not in the USA either,
so various voltages and practices would be inappropriate.
Back in my motor control days, we called them "motor starters". But that may
have been local slang. :-)
On Wed, 15 Jun 2005 09:43:58 -0500, Joe User <[email protected]> wrote:
>I wast just browsing a DC thread where "magnetic switches" are
>discussed. Not the first time I've seen the term, and I know what they
>were talking about, but I DAGS and the first 40 or 50 hits mostly
>related to burglar alarm type switches, and none referred to the "punch
>red for off, punch green for on, don't power the tool up after a power
>failure" type switch that makes sense for woodworking and other
>machinery. Grizzly's web site lists them as magnetic switches, but a
>search at Grainger's web site for "magnetic switch" returned alarm type
>switches and relays, and at McMaster-Carr returned alarm switches. I
>didn't keep searching very long, so I didn't find what I was looking for
>at either site.
>
>I guess what I'm getting around to is a question: Is there another name
>for this type of switch?
>
>They're very simple devices. The actual switch for power to the tool is
>a relay. The relay's coil gets power either through a set of contacts
>on the relay itself, or applied via a normally open momentary switch
>(the "on" button). A normally closed momentary switch in series with
>the coil power is the "off" switch.
>
>A relay with a 110VAC coil and appropriately rated contacts, a NC
>pushbutton (red for off) and a NO pushbutton (green for on) and an
>appropriate enclosure are all you need to make one of these.
>
>If one wanted a separate start/stop switch for the dust collector at
>every tool, it would be easy for the electrically inclined woodworker to
>build a switch that would support a remote start/stop pair for the DC at
>every station. All of the start buttons would be in parallel, while all
>of the stop buttons would be in series (this could be obnoxious if you
>have a bad connection on the "stop" side). I'd probably use a 24VAC for
>the control side, which would mean a 3 pole relay or an extra 24VAC
>transformer.
>
>There are also current sensing controls. Attach one of these devices to
>a power wire on a tool (there is no electrical connection, it senses the
>magnetic field caused by the current flowing through the wire) and use
>it to apply power to the DCs relay. I couldn't find these right off,
>either. anyone know what they're called?
>
>just random thoughts and questions....
>
>-j
____________________
Bill Waller
New Eagle, PA
[email protected]
Joe User wrote:
>I wast just browsing a DC thread where "magnetic switches" are
>discussed. Not the first time I've seen the term, and I know what they
>were talking about, but I DAGS and the first 40 or 50 hits mostly
>related to burglar alarm type switches, and none referred to the "punch
>red for off, punch green for on, don't power the tool up after a power
>failure" type switch that makes sense for woodworking and other
>machinery. Grizzly's web site lists them as magnetic switches, but a
>search at Grainger's web site for "magnetic switch" returned alarm type
>switches and relays, and at McMaster-Carr returned alarm switches. I
>didn't keep searching very long, so I didn't find what I was looking for
>at either site.
>
>I guess what I'm getting around to is a question: Is there another name
>for this type of switch?
<snip>
Try "motor starter" or "NEMA starter".
R,
Tom Q.
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