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
half wave rectifier
Started by ●June 29, 2023
Reply by ●June 29, 20232023-06-29
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". -- Rick C. - Get 1,000 miles of free Supercharging - Tesla referral code - https://ts.la/richard11209
Reply by ●June 29, 20232023-06-29
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. 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
Reply by ●June 29, 20232023-06-29
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.
Reply by ●June 29, 20232023-06-29
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.No, because you have two heaters, which doubles it, cancelling out one of the halves.
Reply by ●June 30, 20232023-06-30
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
Reply by ●June 30, 20232023-06-30
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. > > ..... PhilA 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
Reply by ●June 30, 20232023-06-30
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. -- Rick C. -- Get 1,000 miles of free Supercharging -- Tesla referral code - https://ts.la/richard11209
Reply by ●June 30, 20232023-06-30
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. 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
Reply by ●June 30, 20232023-06-30
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.Yes, you're quite right. -- Cheers Clive
