Contactors/Relays

[David Lesher]

I have futilely been seeking 100A 3ph NC/Form B relays/contactors.
It seems they are all stashed in the "unicorn eggs" box, sigh.

So a second design approach involves dual coil relays. The
flavor I seek has one larger coil to close the relay, and a
second, much lower power holding coil to keep it closed. Of
course, I'm not finding them either. The ones I unearth are
"close coil, open coil" flavor.

Anyone seen such?

 

[legg]

On Sat, 14 Oct 2017 18:16:57 +0000 (UTC), David Lesher
<wb8foz@panix.com> wrote:

I have futilely been seeking 100A 3ph NC/Form B relays/contactors.
It seems they are all stashed in the "unicorn eggs" box, sigh.

So a second design approach involves dual coil relays. The
flavor I seek has one larger coil to close the relay, and a
second, much lower power holding coil to keep it closed. Of
course, I'm not finding them either. The ones I unearth are
"close coil, open coil" flavor.

Anyone seen such?

Are you still insisting on DIN rail mounting?

RL

 

[legg]

On Sat, 14 Oct 2017 18:16:57 +0000 (UTC), David Lesher
<wb8foz@panix.com> wrote:

I have futilely been seeking 100A 3ph NC/Form B relays/contactors.
It seems they are all stashed in the "unicorn eggs" box, sigh.

So a second design approach involves dual coil relays. The
flavor I seek has one larger coil to close the relay, and a
second, much lower power holding coil to keep it closed. Of
course, I'm not finding them either. The ones I unearth are
"close coil, open coil" flavor.

Anyone seen such?

https://www.galco.com/shop/Open-Transfer-Switches

Add your own solenoid.

RL

 

[legg]

On Sat, 14 Oct 2017 18:16:57 +0000 (UTC), David Lesher
<wb8foz@panix.com> wrote:

I have futilely been seeking 100A 3ph NC/Form B relays/contactors.
It seems they are all stashed in the "unicorn eggs" box, sigh.

So a second design approach involves dual coil relays. The
flavor I seek has one larger coil to close the relay, and a
second, much lower power holding coil to keep it closed. Of
course, I'm not finding them either. The ones I unearth are
"close coil, open coil" flavor.

Anyone seen such?

http://gencontrol.co.uk/3-pole--9a-95a--nc1-type-.html

RL

 

[Hul Tytus]

David - are the "close coil, open coil" relays the type that are opened by
a pulse on one coil and closed by a pulse on the other?

Hul

In sci.electronics.design David Lesher <wb8foz@panix.com> wrote:

I have futilely been seeking 100A 3ph NC/Form B relays/contactors.
It seems they are all stashed in the "unicorn eggs" box, sigh.

So a second design approach involves dual coil relays. The
flavor I seek has one larger coil to close the relay, and a
second, much lower power holding coil to keep it closed. Of
course, I'm not finding them either. The ones I unearth are
"close coil, open coil" flavor.

Anyone seen such?

 

[John Larkin]

On Sat, 14 Oct 2017 18:16:57 +0000 (UTC), David Lesher
<wb8foz@panix.com> wrote:

I have futilely been seeking 100A 3ph NC/Form B relays/contactors.
It seems they are all stashed in the "unicorn eggs" box, sigh.

So a second design approach involves dual coil relays. The
flavor I seek has one larger coil to close the relay, and a
second, much lower power holding coil to keep it closed.

AC relays and contactors do that automatically. The seated inductance
is much higher than the open inductance, so the coil current drops
when the relay is fully closed.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

On Sat, 14 Oct 2017 18:16:57 +0000 (UTC), David Lesher
<wb8foz@panix.com> wrote:

I have futilely been seeking 100A 3ph NC/Form B relays/contactors.
It seems they are all stashed in the "unicorn eggs" box, sigh.

So a second design approach involves dual coil relays. The
flavor I seek has one larger coil to close the relay, and a
second, much lower power holding coil to keep it closed. Of
course, I'm not finding them either. The ones I unearth are
"close coil, open coil" flavor.

Anyone seen such?

Have you looked at companies making star/delta soft starter relays ?

You might find some relays with NC or switch over contacts.

 

[Neon John]

On Sat, 14 Oct 2017 18:16:57 +0000 (UTC), David Lesher
<wb8foz@panix.com> wrote:

I have futilely been seeking 100A 3ph NC/Form B relays/contactors.
It seems they are all stashed in the "unicorn eggs" box, sigh.

So a second design approach involves dual coil relays. The
flavor I seek has one larger coil to close the relay, and a
second, much lower power holding coil to keep it closed. Of
course, I'm not finding them either. The ones I unearth are
"close coil, open coil" flavor.

With a DC coil, you can very easily make a peak/hold circuit. Place a
power resistor in series with the coil, the value of which sets the
holding current. Bridge that resistor with a fairly large value
capacitor.

The way it work is that when power is applied, the capacitor shunts
the resistor with zero impedance and supplies full voltage to the
coil. As the capacitor charges, it becomes an open circuit and the
resistor controls the holding current.

The easiest way to select the capacitor is trial and error.

One thing to be aware of. If there is vibration involved then you
must set the holding current high enough to keep the armature pulled
in despite the vibration.

John

John DeArmond
http://www.neon-john.com
http://www.tnduction.com
Tellico Plains, Occupied TN
See website for email address

 

[David Lesher]

legg <legg@nospam.magma.ca> writes:


>Are you still insisting on DIN rail mounting?

No, but that's the least important aspect.... not finding any mounting type...

 

[legg]

On Wed, 18 Oct 2017 22:32:46 +0000 (UTC), David Lesher
<wb8foz@panix.com> wrote:

legg <legg@nospam.magma.ca> writes:


Are you still insisting on DIN rail mounting?

No, but that's the least important aspect.... not finding any mounting type...

This 'fail closed' issue may be a misconception. What mode of failure
are you anticipating this to cover?

If there is energy available on either terminal of the open contacts,
it should be harnessed to develope the required switch circuit state.
If there is no power on either terminal, then its state doesn't
matter.

RL

 

[David Lesher]

legg <legg@nospam.magma.ca> writes:

Anyone seen such?



https://www.galco.com/shop/Open-Transfer-Switches

Add your own solenoid.

Or pay someone to turn it for us....

--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close..........................
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

 

[David Lesher]

legg <legg@nospam.magma.ca> writes:

Anyone seen such?

http://gencontrol.co.uk/3-pole--9a-95a--nc1-type-.html

NO not NC main contacts.
--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close..........................
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

 

[David Lesher]

Hul Tytus <ht@panix.com> writes:

David - are the "close coil, open coil" relays the type that are opened by
a pulse on one coil and closed by a pulse on the other?

Yes....

--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close..........................
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

 

[David Lesher]

legg <legg@nospam.magma.ca> writes:

This 'fail closed' issue may be a misconception. What mode of failure
are you anticipating this to cover?

Nope, it's what's needed....
Control power drops, relay contacts close.


--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close..........................
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

 

[rickman]

David Lesher wrote on 10/19/2017 2:04 AM:

legg <legg@nospam.magma.ca> writes:

Anyone seen such?

http://gencontrol.co.uk/3-pole--9a-95a--nc1-type-.html

NO not NC main contacts.

Now I'm confused. Above you said if control power drops the relay contacts
should close. Here you say they should be NO. Those two things are not
compatible.

--

Rick C

Viewed the eclipse at Wintercrest Farms,
on the centerline of totality since 1998

 

On Wed, 18 Oct 2017 22:32:46 +0000 (UTC), David Lesher
<wb8foz@panix.com> wrote:

legg <legg@nospam.magma.ca> writes:


Are you still insisting on DIN rail mounting?

No, but that's the least important aspect.... not finding any mounting type...

Do you have room for three separate relays each with a single NC
contact ?

 

[legg]

On Thu, 19 Oct 2017 06:11:58 +0000 (UTC), David Lesher
<wb8foz@panix.com> wrote:

legg <legg@nospam.magma.ca> writes:


This 'fail closed' issue may be a misconception. What mode of failure
are you anticipating this to cover?

Nope, it's what's needed....
Control power drops, relay contacts close.

Where does control power come from?
I'd expect use a power fail signal to do it's business during a
hold-up time period.

If there is only control power, then there's nothing to control, so
the normal state, in that condition, should be your 'fail-safe'
default.

RL

 

[rickman]

legg wrote on 10/19/2017 3:02 PM:

On Thu, 19 Oct 2017 06:11:58 +0000 (UTC), David Lesher
wb8foz@panix.com> wrote:

legg <legg@nospam.magma.ca> writes:


This 'fail closed' issue may be a misconception. What mode of failure
are you anticipating this to cover?

Nope, it's what's needed....
Control power drops, relay contacts close.

Where does control power come from?
I'd expect use a power fail signal to do it's business during a
hold-up time period.

If there is only control power, then there's nothing to control, so
the normal state, in that condition, should be your 'fail-safe'
default.

Are you suggesting the relay needs to be powered from the contacts and it
needs to *remember* the state it was last in when control power fails?
Seems simpler to just power the coil from the control side and use a NC
relay. No small part of the use of relays comes from the isolation.
Powering the relay from the load side means you have to start all over again
with an isolation barrier.

--

Rick C

Viewed the eclipse at Wintercrest Farms,
on the centerline of totality since 1998

 

[legg]

On Thu, 19 Oct 2017 18:48:50 -0400, rickman <gnuarm@gmail.com> wrote:

legg wrote on 10/19/2017 3:02 PM:
On Thu, 19 Oct 2017 06:11:58 +0000 (UTC), David Lesher
wb8foz@panix.com> wrote:

legg <legg@nospam.magma.ca> writes:


This 'fail closed' issue may be a misconception. What mode of failure
are you anticipating this to cover?

Nope, it's what's needed....
Control power drops, relay contacts close.

Where does control power come from?
I'd expect use a power fail signal to do it's business during a
hold-up time period.

If there is only control power, then there's nothing to control, so
the normal state, in that condition, should be your 'fail-safe'
default.

Are you suggesting the relay needs to be powered from the contacts and it
needs to *remember* the state it was last in when control power fails?
Seems simpler to just power the coil from the control side and use a NC
relay. No small part of the use of relays comes from the isolation.
Powering the relay from the load side means you have to start all over again
with an isolation barrier.

There's no memory involved. This is the designer's decision. If it is
important that the contacts be in a certain configuration under
certain conditions, then it's the designer's responsibility to provide
circuitry that's smart enough to enforce it.

Intentionally configuring a lower power electronic control circuit
that can't function, always, when the higher-powered controlled
electrical quantity is present doesn't make sense.

RL

 

[legg]

On Thu, 19 Oct 2017 06:07:04 +0000 (UTC), David Lesher
<wb8foz@panix.com> wrote:

Hul Tytus <ht@panix.com> writes:

David - are the "close coil, open coil" relays the type that are opened by
a pulse on one coil and closed by a pulse on the other?

Yes....

That is the usual function of the physical component of an
electronically controlled transfer switch, partly due to the power
requirement of the movement.. The auxilliary signal contacts can
provide information on the operating state and may also be used
directly to energize or disable the appropriate coil.

RL