Snubber needed for triac driving heating element?

[Pimpom]

This is about a triac switching a heater on and off. The heating
element is mostly resistive with a small incidental inductive
component due to the coiled structure. The switching is a simple
on/off operation without phase control. Power is about 2kW. The
interval between switchings range from a few minutes to an hour.

Is a snubber needed or desirable for this? Please consider the
case for random firing and for zero-crossing.

 

On Sunday, April 19, 2020 at 10:41:32 AM UTC-4, Pimpom wrote:

This is about a triac switching a heater on and off. The heating
element is mostly resistive with a small incidental inductive
component due to the coiled structure. The switching is a simple
on/off operation without phase control. Power is about 2kW. The
interval between switchings range from a few minutes to an hour.

Is a snubber needed or desirable for this? Please consider the
case for random firing and for zero-crossing.

Usually a samll L- shunt C (10uH shunt 0.1uF) is added to eliminate excessive EMI from going into the mains, in which case you need a small snubber.

 

[Pimpom]

On 4/19/2020 8:16 PM, bloggs.fredbloggs.fred@gmail.com wrote:

On Sunday, April 19, 2020 at 10:41:32 AM UTC-4, Pimpom wrote:
This is about a triac switching a heater on and off. The heating
element is mostly resistive with a small incidental inductive
component due to the coiled structure. The switching is a simple
on/off operation without phase control. Power is about 2kW. The
interval between switchings range from a few minutes to an hour.

Is a snubber needed or desirable for this? Please consider the
case for random firing and for zero-crossing.

Usually a samll L- shunt C (10uH shunt 0.1uF) is added to eliminate excessive EMI from going into the mains, in which case you need a small snubber.

Thanks for the reply. The unit is to be a replacement for a
mechanical timer that doesn't have any kind of EMI suppression.

 

On Sunday, 19 April 2020 21:09:15 UTC+1, Pimpom wrote:

On 4/19/2020 8:16 PM, bloggs.fredbloggs.fred@gmail.com wrote:
On Sunday, April 19, 2020 at 10:41:32 AM UTC-4, Pimpom wrote:
This is about a triac switching a heater on and off. The heating
element is mostly resistive with a small incidental inductive
component due to the coiled structure. The switching is a simple
on/off operation without phase control. Power is about 2kW. The
interval between switchings range from a few minutes to an hour.

Is a snubber needed or desirable for this? Please consider the
case for random firing and for zero-crossing.

Usually a samll L- shunt C (10uH shunt 0.1uF) is added to eliminate excessive EMI from going into the mains, in which case you need a small snubber.


Thanks for the reply. The unit is to be a replacement for a
mechanical timer that doesn't have any kind of EMI suppression.

At switch-on this is no different from a mechanical switch being turned on,
except that a triac doesn't have contact bounce. Switch off will always
happen close to zero crossings, so this is also better than a normal switch
from an EMC point of view. You would not normally fit a snubber to a
mechanical switch and there is even less need to fit one here.

John

 

[Flyguy]

On Sunday, April 19, 2020 at 7:41:32 AM UTC-7, Pimpom wrote:

This is about a triac switching a heater on and off. The heating
element is mostly resistive with a small incidental inductive
component due to the coiled structure. The switching is a simple
on/off operation without phase control. Power is about 2kW. The
interval between switchings range from a few minutes to an hour.

Is a snubber needed or desirable for this? Please consider the
case for random firing and for zero-crossing.

You didn't say whether it is AC or DC. If AC you can add a zero crossing detector. In any case, check this out:

https://www.arcsuppressiontechnologies.com/

 

[Ricky C]

On Sunday, April 19, 2020 at 10:41:32 AM UTC-4, Pimpom wrote:

This is about a triac switching a heater on and off. The heating
element is mostly resistive with a small incidental inductive
component due to the coiled structure. The switching is a simple
on/off operation without phase control. Power is about 2kW. The
interval between switchings range from a few minutes to an hour.

Is a snubber needed or desirable for this? Please consider the
case for random firing and for zero-crossing.

What type of device is controlling the on/off signal? It probably wouldn't be too hard to add zero crossing detection. But why bother? At 2 kW I take it this is a 240 volt heater? I'm guessing a UK tea kettle auto turn on for morning brew?

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

 

[Phil Allison]

Flyguy is a Fake wrote:

=========================

You didn't say whether it is AC or DC.

** Whaatttttt ???????????????

Must be from Plant Claire.



...... Phil

 

[Ricky C]

On Monday, April 20, 2020 at 2:48:31 AM UTC-4, Flyguy wrote:

On Sunday, April 19, 2020 at 11:46:48 PM UTC-7, Phil Allison wrote:
Flyguy is a Fake wrote:

=========================


You didn't say whether it is AC or DC.


** Whaatttttt ???????????????

Must be from Plant Claire.



..... Phil

...and you must be from MARS! What a DOLT!!

You would not use a triac to control DC.

--

Rick C.

+ Get 1,000 miles of free Supercharging
+ Tesla referral code - https://ts.la/richard11209

 

Flyguy <soar2morrow@yahoo.com> wrote in news:513ab216-2eb5-4b4d-b50c-
e892c9d9c1f9@googlegroups.com:

On Sunday, April 19, 2020 at 11:46:48 PM UTC-7, Phil Allison wrote:
Flyguy is a Fake wrote:

=========================


You didn't say whether it is AC or DC.


** Whaatttttt ???????????????

Must be from Plant Claire.



..... Phil

...and you must be from MARS! What a DOLT!!

Phil is 5 orders of magintude more intelligent than you are.

 

[Flyguy]

On Sunday, April 19, 2020 at 11:46:48 PM UTC-7, Phil Allison wrote:

Flyguy is a Fake wrote:

=========================


You didn't say whether it is AC or DC.


** Whaatttttt ???????????????

Must be from Plant Claire.



..... Phil

....and you must be from MARS! What a DOLT!!

 

[Ricky C]

On Monday, April 20, 2020 at 3:41:23 AM UTC-4, DecadentLinux...@decadence.org wrote:

Flyguy <soar2morrow@yahoo.com> wrote in news:513ab216-2eb5-4b4d-b50c-
e892c9d9c1f9@googlegroups.com:

On Sunday, April 19, 2020 at 11:46:48 PM UTC-7, Phil Allison wrote:
Flyguy is a Fake wrote:

=========================


You didn't say whether it is AC or DC.


** Whaatttttt ???????????????

Must be from Plant Claire.



..... Phil

...and you must be from MARS! What a DOLT!!


Phil is 5 orders of magintude more intelligent than you are.

Which one are you trying to insult?

--

Rick C.

-- Get 1,000 miles of free Supercharging
-- Tesla referral code - https://ts.la/richard11209

 

[Pimpom]

On 4/20/2020 11:05 AM, Ricky C wrote:

On Sunday, April 19, 2020 at 10:41:32 AM UTC-4, Pimpom wrote:
This is about a triac switching a heater on and off. The heating
element is mostly resistive with a small incidental inductive
component due to the coiled structure. The switching is a simple
on/off operation without phase control. Power is about 2kW. The
interval between switchings range from a few minutes to an hour.

Is a snubber needed or desirable for this? Please consider the
case for random firing and for zero-crossing.

What type of device is controlling the on/off signal?

A simple digital timer switching an MOC3023 triac driver,
probably a 4060 rather than a uC for such a simple job. The triac
is a BTA41.

> It probably wouldn't be too hard to add zero crossing detection. But why bother?

Exactly. I have random couplers in stock but not zero-crossing ones.

At 2 kW I take it this is a 240 volt heater? I'm guessing a UK tea kettle auto turn on for morning
brew?

A convection (not microwave) oven for my daughter, a psychologist
who sometimes dabbles in baking and is now really into it during
the lockdown. The clockwork timer on her oven is behaving
erratically. Indian 230V.

 

Ricky C <gnuarm.deletethisbit@gmail.com> wrote in
news:18e79abe-45ea-4a27-9b27-4fe83c724246@googlegroups.com:

On Monday, April 20, 2020 at 3:41:23 AM UTC-4,
DecadentLinux...@decadence.org wrote:
Flyguy <soar2morrow@yahoo.com> wrote in
news:513ab216-2eb5-4b4d-b50c- e892c9d9c1f9@googlegroups.com:

On Sunday, April 19, 2020 at 11:46:48 PM UTC-7, Phil Allison
wrote:
Flyguy is a Fake wrote:

=========================


You didn't say whether it is AC or DC.


** Whaatttttt ???????????????

Must be from Plant Claire.



..... Phil

...and you must be from MARS! What a DOLT!!


Phil is 5 orders of magintude more intelligent than you are.

Which one are you trying to insult?

Good point. 5 decimal shifts on a zero is still zero.
Funny to see FlyShit calling someone a dolt.

 

[Chris Jones]

On 20/04/2020 17:19, Ricky C wrote:

On Monday, April 20, 2020 at 2:48:31 AM UTC-4, Flyguy wrote:
On Sunday, April 19, 2020 at 11:46:48 PM UTC-7, Phil Allison wrote:
Flyguy is a Fake wrote:

=========================


You didn't say whether it is AC or DC.


** Whaatttttt ???????????????

Must be from Plant Claire.



..... Phil

...and you must be from MARS! What a DOLT!!

You would not use a triac to control DC.

Only once.

 

[Chris Jones]

On 20/04/2020 20:11, Pimpom wrote:

On 4/20/2020 11:05 AM, Ricky C wrote:
On Sunday, April 19, 2020 at 10:41:32 AM UTC-4, Pimpom wrote:
This is about a triac switching a heater on and off. The heating
element is mostly resistive with a small incidental inductive
component due to the coiled structure. The switching is a simple
on/off operation without phase control. Power is about 2kW. The
interval between switchings range from a few minutes to an hour.

Is a snubber needed or desirable for this? Please consider the
case for random firing and for zero-crossing.

What type of device is controlling the on/off signal?

A simple digital timer switching an MOC3023 triac driver, probably a
4060 rather than a uC for such a simple job. The triac is a BTA41.

It probably wouldn't be too hard to add zero crossing detection.  But
why bother?

Exactly. I have random couplers in stock but not zero-crossing ones.

At 2 kW I take it this is a 240 volt heater?  I'm guessing a UK tea
kettle auto turn on for morning brew?

A convection (not microwave) oven for my daughter, a psychologist who
sometimes dabbles in baking and is now really into it during the
lockdown. The clockwork timer on her oven is behaving erratically.
Indian 230V.

Do not trust the TRIAC to stay off where it performs a safety function,
though. A mains spike during the night might melt the TRIAC into a short
circuit, and you could have the same experience as these people, albeit
at a more reasonable price:


https://www.theverge.com/2019/8/14/20802774/june-smart-oven-remote-preheat-update-user-error

Whilst relay contacts can weld together and stay on when they shouldn't,
still, I would have more trust in a relay than a TRIAC to stay off once
the user (or a supervisory circuit) has confirmed that it is already off.

 

[Ricky C]

On Monday, April 20, 2020 at 6:11:41 AM UTC-4, Pimpom wrote:

On 4/20/2020 11:05 AM, Ricky C wrote:
On Sunday, April 19, 2020 at 10:41:32 AM UTC-4, Pimpom wrote:
This is about a triac switching a heater on and off. The heating
element is mostly resistive with a small incidental inductive
component due to the coiled structure. The switching is a simple
on/off operation without phase control. Power is about 2kW. The
interval between switchings range from a few minutes to an hour.

Is a snubber needed or desirable for this? Please consider the
case for random firing and for zero-crossing.

What type of device is controlling the on/off signal?

A simple digital timer switching an MOC3023 triac driver,
probably a 4060 rather than a uC for such a simple job. The triac
is a BTA41.

So the timer is a black box with some sort of output? I guess no option to add the zero cross detection in that.

It probably wouldn't be too hard to add zero crossing detection. But why bother?

Exactly. I have random couplers in stock but not zero-crossing ones.

You could just buy a contactor (relay). Simple and effective. They even have 240 volt relays with 12 volt drive. Maybe even 5 volt drive.

At 2 kW I take it this is a 240 volt heater? I'm guessing a UK tea kettle auto turn on for morning
brew?

A convection (not microwave) oven for my daughter,

So 240 volts? Here in the US you can get about 1.4 kW from a 15 amp 120 volt outlet or 19 kW from a 20 amp outlet. Most kitchen stuff is 240 volts. Are you US or UK?

a psychologist
who sometimes dabbles in baking and is now really into it during
the lockdown. The clockwork timer on her oven is behaving
erratically. Indian 230V.

Why a timer??? Every oven I've ever owned has had a timer on it (seems obligatory somehow) but I have not once in 50 years used it. Can't she just set a kitchen timer and turn it off herself?

Where does she live? I'd like to go over for fresh baked bread once this is over. Or even just cookies. Mmmmm...

I've run out of not food exactly, but variety. So I should be going out today to shop. I am so sick of eating my own cooking. I believe I can get some carry out to bring home. I need to find some good restaurants near the store.

--

Rick C.

-+ Get 1,000 miles of free Supercharging
-+ Tesla referral code - https://ts.la/richard11209

 

[Pimpom]

On 4/20/2020 7:22 PM, Chris Jones wrote:

On 20/04/2020 20:11, Pimpom wrote:
On 4/20/2020 11:05 AM, Ricky C wrote:
On Sunday, April 19, 2020 at 10:41:32 AM UTC-4, Pimpom wrote:
This is about a triac switching a heater on and off. The heating
element is mostly resistive with a small incidental inductive
component due to the coiled structure. The switching is a simple
on/off operation without phase control. Power is about 2kW. The
interval between switchings range from a few minutes to an hour.

Is a snubber needed or desirable for this? Please consider the
case for random firing and for zero-crossing.

What type of device is controlling the on/off signal?

A simple digital timer switching an MOC3023 triac driver, probably a
4060 rather than a uC for such a simple job. The triac is a BTA41.

It probably wouldn't be too hard to add zero crossing detection.  But
why bother?

Exactly. I have random couplers in stock but not zero-crossing ones.

At 2 kW I take it this is a 240 volt heater?  I'm guessing a UK tea
kettle auto turn on for morning brew?

A convection (not microwave) oven for my daughter, a psychologist who
sometimes dabbles in baking and is now really into it during the
lockdown. The clockwork timer on her oven is behaving erratically.
Indian 230V.

Do not trust the TRIAC to stay off where it performs a safety function,
though. A mains spike during the night might melt the TRIAC into a short
circuit, and you could have the same experience as these people, albeit
at a more reasonable price:


https://www.theverge.com/2019/8/14/20802774/june-smart-oven-remote-preheat-update-user-error

Whilst relay contacts can weld together and stay on when they shouldn't,
still, I would have more trust in a relay than a TRIAC to stay off once
the user (or a supervisory circuit) has confirmed that it is already off.

This is strictly for use in my household where all loads
including TVs and computers are always switched off at the plug
when not in use.

I'd prefer to use a relay, if only to obviate the need for a
sizeable heatsink for the triac but I don't have any suitable
ones. I do have some no-name 25A units but I wouldn't trust them
to handle 9A on a regular basis.

 

[Ricky C]

On Monday, April 20, 2020 at 9:52:40 AM UTC-4, Chris Jones wrote:

On 20/04/2020 20:11, Pimpom wrote:
On 4/20/2020 11:05 AM, Ricky C wrote:
On Sunday, April 19, 2020 at 10:41:32 AM UTC-4, Pimpom wrote:
This is about a triac switching a heater on and off. The heating
element is mostly resistive with a small incidental inductive
component due to the coiled structure. The switching is a simple
on/off operation without phase control. Power is about 2kW. The
interval between switchings range from a few minutes to an hour.

Is a snubber needed or desirable for this? Please consider the
case for random firing and for zero-crossing.

What type of device is controlling the on/off signal?

A simple digital timer switching an MOC3023 triac driver, probably a
4060 rather than a uC for such a simple job. The triac is a BTA41.

It probably wouldn't be too hard to add zero crossing detection.  But
why bother?

Exactly. I have random couplers in stock but not zero-crossing ones.

At 2 kW I take it this is a 240 volt heater?  I'm guessing a UK tea
kettle auto turn on for morning brew?

A convection (not microwave) oven for my daughter, a psychologist who
sometimes dabbles in baking and is now really into it during the
lockdown. The clockwork timer on her oven is behaving erratically.
Indian 230V.

Do not trust the TRIAC to stay off where it performs a safety function,
though. A mains spike during the night might melt the TRIAC into a short
circuit, and you could have the same experience as these people, albeit
at a more reasonable price:


https://www.theverge.com/2019/8/14/20802774/june-smart-oven-remote-preheat-update-user-error

Strange. “It’s a really wonderful feature to be able to remotely preheat your oven" Really? WTF?

Whilst relay contacts can weld together and stay on when they shouldn't,
still, I would have more trust in a relay than a TRIAC to stay off once
the user (or a supervisory circuit) has confirmed that it is already off.

Even if a triac were to trigger on from a power line spike, it doesn't stay on. It turns off at the next zero crossing. No? It would have to be a scramble in the controlling circuit to make it come on for more than an instant which is what the Verge article is about. That can happen even with a relay.

--

Rick C.

+- Get 1,000 miles of free Supercharging
+- Tesla referral code - https://ts.la/richard11209

 

[Ricky C]

On Monday, April 20, 2020 at 11:29:23 AM UTC-4, Pimpom wrote:

On 4/20/2020 7:22 PM, Chris Jones wrote:
On 20/04/2020 20:11, Pimpom wrote:
On 4/20/2020 11:05 AM, Ricky C wrote:
On Sunday, April 19, 2020 at 10:41:32 AM UTC-4, Pimpom wrote:
This is about a triac switching a heater on and off. The heating
element is mostly resistive with a small incidental inductive
component due to the coiled structure. The switching is a simple
on/off operation without phase control. Power is about 2kW. The
interval between switchings range from a few minutes to an hour.

Is a snubber needed or desirable for this? Please consider the
case for random firing and for zero-crossing.

What type of device is controlling the on/off signal?

A simple digital timer switching an MOC3023 triac driver, probably a
4060 rather than a uC for such a simple job. The triac is a BTA41.

It probably wouldn't be too hard to add zero crossing detection.  But
why bother?

Exactly. I have random couplers in stock but not zero-crossing ones.

At 2 kW I take it this is a 240 volt heater?  I'm guessing a UK tea
kettle auto turn on for morning brew?

A convection (not microwave) oven for my daughter, a psychologist who
sometimes dabbles in baking and is now really into it during the
lockdown. The clockwork timer on her oven is behaving erratically.
Indian 230V.

Do not trust the TRIAC to stay off where it performs a safety function,
though. A mains spike during the night might melt the TRIAC into a short
circuit, and you could have the same experience as these people, albeit
at a more reasonable price:


https://www.theverge.com/2019/8/14/20802774/june-smart-oven-remote-preheat-update-user-error

Whilst relay contacts can weld together and stay on when they shouldn't,
still, I would have more trust in a relay than a TRIAC to stay off once
the user (or a supervisory circuit) has confirmed that it is already off.

This is strictly for use in my household where all loads
including TVs and computers are always switched off at the plug
when not in use.

I'd prefer to use a relay, if only to obviate the need for a
sizeable heatsink for the triac but I don't have any suitable
ones. I do have some no-name 25A units but I wouldn't trust them
to handle 9A on a regular basis.

Switching on and off a couple of times a day is not exactly a heavy duty work load. Why not order a suitable relay? I've always liked the reassuring sound of the relay clicking which often helps isolate faults when the durn appliance isn't working.

--

Rick C.

++ Get 1,000 miles of free Supercharging
++ Tesla referral code - https://ts.la/richard11209

 

[legg]

On Mon, 20 Apr 2020 15:41:30 +0530, Pimpom <nobody@nowhere.com> wrote:

On 4/20/2020 11:05 AM, Ricky C wrote:
On Sunday, April 19, 2020 at 10:41:32 AM UTC-4, Pimpom wrote:
This is about a triac switching a heater on and off. The heating
element is mostly resistive with a small incidental inductive
component due to the coiled structure. The switching is a simple
on/off operation without phase control. Power is about 2kW. The
interval between switchings range from a few minutes to an hour.

Is a snubber needed or desirable for this? Please consider the
case for random firing and for zero-crossing.

What type of device is controlling the on/off signal?

A simple digital timer switching an MOC3023 triac driver,
probably a 4060 rather than a uC for such a simple job. The triac
is a BTA41.

It probably wouldn't be too hard to add zero crossing detection. But why bother?

Exactly. I have random couplers in stock but not zero-crossing ones.

At 2 kW I take it this is a 240 volt heater? I'm guessing a UK tea kettle auto turn on for morning
brew?

A convection (not microwave) oven for my daughter, a psychologist
who sometimes dabbles in baking and is now really into it during
the lockdown. The clockwork timer on her oven is behaving
erratically. Indian 230V.

A triac is inherently zero current (or reverse current)switching.
To prevent dv/dt for reactive loads, a simple RC snubber should
normally suffice.

RL