half wave rectifier...

T

TTman

Guest
As part of an experiment with solar, I want to drive my 220V 3kW
immersion heater with a suitable diode so that the effective power is
~1.5kW and can be driven by a smart switch so that it doesn\'t suck too
much out of the 9.5kWh battery or solar panels.. What diode? This is UK
spec.

--
This email has been checked for viruses by Avast antivirus software.
www.avast.com
 
On Thursday, June 29, 2023 at 6:37:31 PM UTC-4, TTman wrote:
As part of an experiment with solar, I want to drive my 220V 3kW
immersion heater with a suitable diode so that the effective power is
~1.5kW and can be driven by a smart switch so that it doesn\'t suck too
much out of the 9.5kWh battery or solar panels.. What diode? This is UK
spec.
Click to expand...

You can do that, or... you can string two heaters in series. Doubling the resistance will cut the power in half. It will also cut the current in half. Using a diode will not change the peak current, which may be a problem with a \"smart switch\".

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209
 
On Thursday, June 29, 2023 at 3:47:03 PM UTC-7, Ricky wrote:
On Thursday, June 29, 2023 at 6:37:31 PM UTC-4, TTman wrote:
As part of an experiment with solar, I want to drive my 220V 3kW
immersion heater with a suitable diode so that the effective power is
~1.5kW and can be driven by a smart switch so that it doesn\'t suck too
much out of the 9.5kWh battery or solar panels.. What diode? This is UK
spec.
You can do that, or... you can string two heaters in series. Doubling the resistance will cut the power in half.
Click to expand...

Power by half of half.

Anyway, this diode should work and I am using it for full bridge rectifier to pull maximum power out of my 220V inverter.

https://www.newark.com/solid-state/25f40/standard-diode-25a-400v-do-4/dp/07R9506
 
On Thu, 29 Jun 2023 23:37:22 +0100, TTman <kraken.sankey@gmail.com>
wrote:

As part of an experiment with solar, I want to drive my 220V 3kW
immersion heater with a suitable diode so that the effective power is
~1.5kW and can be driven by a smart switch so that it doesn\'t suck too
much out of the 9.5kWh battery or solar panels.. What diode? This is UK
spec.
Click to expand...

Is the source the AC line, what you folks call \"mains\" ?

If not, the DC component could be a problem.

I have conjectured that a lot of DC current will slow down an electric
meter, disk or electronic.
 
Eddy Lee <eddy711lee@gmail.com> writes:
You can do that, or... you can string two heaters in series. Doubling the resistance will cut the power in half.

Power by half of half.
Click to expand...

No, because you have two heaters, which doubles it, cancelling out one
of the halves.
 
On Thursday, June 29, 2023 at 6:57:22 PM UTC-4, Eddy Lee wrote:
On Thursday, June 29, 2023 at 3:47:03 PM UTC-7, Ricky wrote:
On Thursday, June 29, 2023 at 6:37:31 PM UTC-4, TTman wrote:
As part of an experiment with solar, I want to drive my 220V 3kW
immersion heater with a suitable diode so that the effective power is
~1.5kW and can be driven by a smart switch so that it doesn\'t suck too
much out of the 9.5kWh battery or solar panels.. What diode? This is UK
spec.
You can do that, or... you can string two heaters in series. Doubling the resistance will cut the power in half.
Power by half of half.
Click to expand...

As usual, you fail to understand.

P = E^2 / R

If you string two heaters in series, you have the same voltage, but twice the resistance, so half the power.

--

Rick C.

+ Get 1,000 miles of free Supercharging
+ Tesla referral code - https://ts.la/richard11209
 
Eddy Lee wrote:
-----------------------
Anyway, this diode should work and I am using it for full bridge rectifier to pull maximum power out of my 220V inverter.

https://www.newark.com/solid-state/25f40/standard-diode-25a-400v-do-4/dp/07R9506
Click to expand...

** Ah - a stud ( or bolt ) style diode.
It will need a fair size heatsink, threaded at 10-32 UNF.
BTW the heatsink will be live and dangerous.

OTOH, a 25A, 600V metal base bridge rectifier is isolated from the AC power and can be attached to an earthed box or heatsink with any suitable bolt. Just use the + and - terminals.

...... Phil
 
On 30/06/2023 05:23, Ricky wrote:
On Thursday, June 29, 2023 at 6:57:22 PM UTC-4, Eddy Lee wrote:
On Thursday, June 29, 2023 at 3:47:03 PM UTC-7, Ricky wrote:
On Thursday, June 29, 2023 at 6:37:31 PM UTC-4, TTman wrote:
As part of an experiment with solar, I want to drive my 220V 3kW
immersion heater with a suitable diode so that the effective power is
~1.5kW and can be driven by a smart switch so that it doesn\'t suck too
much out of the 9.5kWh battery or solar panels.. What diode? This is UK
spec.
You can do that, or... you can string two heaters in series. Doubling the resistance will cut the power in half.
Power by half of half.

As usual, you fail to understand.

P = E^2 / R

If you string two heaters in series, you have the same voltage, but twice the resistance, so half the power.
Click to expand...

If you have two heaters in series, each sees half the voltage.

--
Cheers
Clive
 
On 2023-06-30 08:35, Phil Allison wrote:
Eddy Lee wrote:
-----------------------

Anyway, this diode should work and I am using it for full bridge rectifier to pull maximum power out of my 220V inverter.

https://www.newark.com/solid-state/25f40/standard-diode-25a-400v-do-4/dp/07R9506

** Ah - a stud ( or bolt ) style diode.
It will need a fair size heatsink, threaded at 10-32 UNF.
BTW the heatsink will be live and dangerous.

OTOH, a 25A, 600V metal base bridge rectifier is isolated from the AC power and can be attached to an earthed box or heatsink with any suitable bolt. Just use the + and - terminals.

..... Phil
Click to expand...

A good idea, the proper isolation to the heat sink is already present.

Or better, for half the voltage drop, so half the dissipation, use (+) and (both of the ~ connected together).

Note that this rectifier method produces a DC component on the mains. This may play havoc with transformers and motors on that same mains.

I\'ve made phase and PWM controllers for kW heaters on 3 phase systems, and had to be careful to keep things balanced.
Also, phase control causes EMI, and PWM control (for whole cycles) causes flickering.

Arie
 
On Friday, June 30, 2023 at 3:09:43 AM UTC-4, Clive Arthur wrote:
On 30/06/2023 05:23, Ricky wrote:
On Thursday, June 29, 2023 at 6:57:22 PM UTC-4, Eddy Lee wrote:
On Thursday, June 29, 2023 at 3:47:03 PM UTC-7, Ricky wrote:
On Thursday, June 29, 2023 at 6:37:31 PM UTC-4, TTman wrote:
As part of an experiment with solar, I want to drive my 220V 3kW
immersion heater with a suitable diode so that the effective power is
~1.5kW and can be driven by a smart switch so that it doesn\'t suck too
much out of the 9.5kWh battery or solar panels.. What diode? This is UK
spec.
You can do that, or... you can string two heaters in series. Doubling the resistance will cut the power in half.
Power by half of half.

As usual, you fail to understand.

P = E^2 / R

If you string two heaters in series, you have the same voltage, but twice the resistance, so half the power.

If you have two heaters in series, each sees half the voltage.
Click to expand...

Yes, that is correct. Not very relevant, but correct.

Do you see something wrong with the equation I presented? If you double the value of R, while holding E constant, P will be halved. No?

There\'s no need at all, to focus on one heater, unless there is some constraint in the mechanical design that puts the other heater in a different location.

--

Rick C.

-- Get 1,000 miles of free Supercharging
-- Tesla referral code - https://ts.la/richard11209
 
Arie de Muijnck wrote:
----------------------------------
Anyway, this diode should work and I am using it for full bridge rectifier to pull maximum power out of my 220V inverter.

https://www.newark.com/solid-state/25f40/standard-diode-25a-400v-do-4/dp/07R9506

** Ah - a stud ( or bolt ) style diode.
It will need a fair size heatsink, threaded at 10-32 UNF.
BTW the heatsink will be live and dangerous.

OTOH, a 25A, 600V metal base bridge rectifier is isolated from the AC power and can be attached to an earthed box or heatsink with any suitable bolt. Just use the + and - terminals.


A good idea, the proper isolation to the heat sink is already present.
Click to expand...

** Huh?? Wow do you know that ?

> Or better, for half the voltage drop, so half the dissipation, use (+) and (both of the ~ connected together).

** Might stress the reverse voltage handing of the diodes.

Note that this rectifier method produces a DC component on the mains.
This may play havoc with transformers and motors on that same mains.
Click to expand...

** But the OP is not using the mains.

The DC offset effect you allude to is fairly small and rarely a problem.
I have a 1600W hot air gun that uses the same trick to reduce the air temp.



....... Phil
 
On 30/06/2023 08:31, Ricky wrote:
On Friday, June 30, 2023 at 3:09:43 AM UTC-4, Clive Arthur wrote:
On 30/06/2023 05:23, Ricky wrote:
On Thursday, June 29, 2023 at 6:57:22 PM UTC-4, Eddy Lee wrote:
On Thursday, June 29, 2023 at 3:47:03 PM UTC-7, Ricky wrote:
On Thursday, June 29, 2023 at 6:37:31 PM UTC-4, TTman wrote:
As part of an experiment with solar, I want to drive my 220V 3kW
immersion heater with a suitable diode so that the effective power is
~1.5kW and can be driven by a smart switch so that it doesn\'t suck too
much out of the 9.5kWh battery or solar panels.. What diode? This is UK
spec.
You can do that, or... you can string two heaters in series. Doubling the resistance will cut the power in half.
Power by half of half.

As usual, you fail to understand.

P = E^2 / R

If you string two heaters in series, you have the same voltage, but twice the resistance, so half the power.

If you have two heaters in series, each sees half the voltage.

Yes, that is correct. Not very relevant, but correct.

Do you see something wrong with the equation I presented? If you double the value of R, while holding E constant, P will be halved. No?

There\'s no need at all, to focus on one heater, unless there is some constraint in the mechanical design that puts the other heater in a different location.
Click to expand...

Yes, you\'re quite right.

--
Cheers
Clive
 
On 29/06/2023 23:46, Ricky wrote:
On Thursday, June 29, 2023 at 6:37:31 PM UTC-4, TTman wrote:
As part of an experiment with solar, I want to drive my 220V 3kW
immersion heater with a suitable diode so that the effective power is
~1.5kW and can be driven by a smart switch so that it doesn\'t suck too
much out of the 9.5kWh battery or solar panels.. What diode? This is UK
spec.

You can do that, or... you can string two heaters in series. Doubling the resistance will cut the power in half. It will also cut the current in half. Using a diode will not change the peak current, which may be a problem with a \"smart switch\".

Can\'t do that. The heater element is inside a copper tank.
Click to expand...

--
This email has been checked for viruses by Avast antivirus software.
www.avast.com
 
On 30/06/2023 05:23, Ricky wrote:
On Thursday, June 29, 2023 at 6:57:22 PM UTC-4, Eddy Lee wrote:
On Thursday, June 29, 2023 at 3:47:03 PM UTC-7, Ricky wrote:
On Thursday, June 29, 2023 at 6:37:31 PM UTC-4, TTman wrote:
As part of an experiment with solar, I want to drive my 220V 3kW
immersion heater with a suitable diode so that the effective power is
~1.5kW and can be driven by a smart switch so that it doesn\'t suck too
much out of the 9.5kWh battery or solar panels.. What diode? This is UK
spec.
You can do that, or... you can string two heaters in series. Doubling the resistance will cut the power in half.
Power by half of half.

As usual, you fail to understand.

P = E^2 / R

If you string two heaters in series, you have the same voltage, but twice the resistance, so half the power.

No, you don\'t understand this english stuff. Twin heaters are rare in the UK
Click to expand...


--
This email has been checked for viruses by Avast antivirus software.
www.avast.com
 
On 30/06/2023 09:02, Phil Allison wrote:
Arie de Muijnck wrote:
----------------------------------

Anyway, this diode should work and I am using it for full bridge rectifier to pull maximum power out of my 220V inverter.

https://www.newark.com/solid-state/25f40/standard-diode-25a-400v-do-4/dp/07R9506

** Ah - a stud ( or bolt ) style diode.
It will need a fair size heatsink, threaded at 10-32 UNF.
BTW the heatsink will be live and dangerous.

OTOH, a 25A, 600V metal base bridge rectifier is isolated from the AC power and can be attached to an earthed box or heatsink with any suitable bolt. Just use the + and - terminals.


A good idea, the proper isolation to the heat sink is already present.

** Huh?? Wow do you know that ?

Or better, for half the voltage drop, so half the dissipation, use (+) and (both of the ~ connected together).

** Might stress the reverse voltage handing of the diodes.


Note that this rectifier method produces a DC component on the mains.
This may play havoc with transformers and motors on that same mains.

** But the OP is not using the mains.
Click to expand...

Yes, it is a houshold mains application..
The DC offset effect you allude to is fairly small and rarely a problem.
I have a 1600W hot air gun that uses the same trick to reduce the air temp.



...... Phil
Click to expand...

--
This email has been checked for viruses by Avast antivirus software.
www.avast.com
 
On 30/06/2023 00:04, John Larkin wrote:
On Thu, 29 Jun 2023 23:37:22 +0100, TTman <kraken.sankey@gmail.com
wrote:

As part of an experiment with solar, I want to drive my 220V 3kW
immersion heater with a suitable diode so that the effective power is
~1.5kW and can be driven by a smart switch so that it doesn\'t suck too
much out of the 9.5kWh battery or solar panels.. What diode? This is UK
spec.

Is the source the AC line, what you folks call \"mains\" ?

If not, the DC component could be a problem.

I have conjectured that a lot of DC current will slow down an electric
meter, disk or electronic.

Yes, AC line, 220/250V 50Hz.Mains :)
Click to expand...

--
This email has been checked for viruses by Avast antivirus software.
www.avast.com
 
On Friday, June 30, 2023 at 5:52:32 AM UTC-4, TTman wrote:
On 30/06/2023 05:23, Ricky wrote:
On Thursday, June 29, 2023 at 6:57:22 PM UTC-4, Eddy Lee wrote:
On Thursday, June 29, 2023 at 3:47:03 PM UTC-7, Ricky wrote:
On Thursday, June 29, 2023 at 6:37:31 PM UTC-4, TTman wrote:
As part of an experiment with solar, I want to drive my 220V 3kW
immersion heater with a suitable diode so that the effective power is
~1.5kW and can be driven by a smart switch so that it doesn\'t suck too
much out of the 9.5kWh battery or solar panels.. What diode? This is UK
spec.
You can do that, or... you can string two heaters in series. Doubling the resistance will cut the power in half.
Power by half of half.

As usual, you fail to understand.

P = E^2 / R

If you string two heaters in series, you have the same voltage, but twice the resistance, so half the power.

No, you don\'t understand this english stuff. Twin heaters are rare in the UK
Click to expand...

Not sure what you are talking about. You want to rig a diode to create half wave AC to drive a heater. That\'s not exactly \"standard\" practice anywhere.

If you have mechanical limitations, that\'s what you have. Electrically, this makes sense.

You could add a resistance in series. It would need to be about 30% of the resistance of the heater. The main element would dissipate half of the original heat. The heat in this added resistance would be about 22% of the heat dissipated in the original heating element. One nice thing about this is that you can tailor the heat in the main element to other than half the original heat level.

--

Rick C.

-+ Get 1,000 miles of free Supercharging
-+ Tesla referral code - https://ts.la/richard11209
 
TTman wrotr:
-------------------
Note that this rectifier method produces a DC component on the mains.
This may play havoc with transformers and motors on that same mains.

** But the OP is not using the mains.

Yes, it is a houshold mains application..
Click to expand...

** Remember posting this?

\" As part of an experiment with solar, I want to drive my 220V 3kW
immersion heater with a suitable diode so that the effective power is
~1.5kW and can be driven by a smart switch so that it doesn\'t suck too
much out of the 9.5kWh battery or solar panels. \"

I see the words \"experiment \" , \" solar \" & \"battery\" but no sign of the word \"mains\".



........ Phil
 
On a sunny day (Fri, 30 Jun 2023 10:55:12 +0100) it happened TTman
<kraken.sankey@gmail.com> wrote in <u7m8q1$2gqfg$4@dont-email.me>:

On 30/06/2023 00:04, John Larkin wrote:
On Thu, 29 Jun 2023 23:37:22 +0100, TTman <kraken.sankey@gmail.com
wrote:

As part of an experiment with solar, I want to drive my 220V 3kW
immersion heater with a suitable diode so that the effective power is
~1.5kW and can be driven by a smart switch so that it doesn\'t suck too
much out of the 9.5kWh battery or solar panels.. What diode? This is UK
spec.

Is the source the AC line, what you folks call \"mains\" ?

If not, the DC component could be a problem.

I have conjectured that a lot of DC current will slow down an electric
meter, disk or electronic.

Yes, AC line, 220/250V 50Hz.Mains :)
Click to expand...

I\'d prefer a triac over a diode to limit any DC (saturation inductors etc)
Google has many examples, here is one:
https://www.homemade-circuits.com/how-to-make-25-amp-1500-watts-heater/
 
TTman wrote:
-------------------------
As part of an experiment with solar, I want to drive my 220V 3kW
immersion heater with a suitable diode so that the effective power is
~1.5kW and can be driven by a smart switch so that it doesn\'t suck too
much out of the 9.5kWh battery or solar panels.. What diode? This is UK
spec.

Is the source the AC line, what you folks call \"mains\" ?

If not, the DC component could be a problem.

I have conjectured that a lot of DC current will slow down an electric
meter, disk or electronic.

Yes, AC line, 220/250V 50Hz.Mains :)
Click to expand...

** Think the idea creates an illegal mains installation.
The DC component and harmonic currents are both way too large too comply with UK regulations.
Also , you may cook your grid tie inverter.



....... Phil
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top