Water heater element?

[stu]

I want to use the element in a hot water heater as a dump load. If the
element is 240VAC 2400W and I am dumping 30V 3 phase DC, am I limited to
the current of the element at 240V? 2400/240=10A?
Thanks

*by 3 phase DC I of course me rectified 3 phase

 

[M Q]

I want to use the element in a hot water heater as a dump load. If the
element is 240VAC 2400W and I am dumping 30V 3 phase DC, am I limited to
the current of the element at 240V? 2400/240=10A?
Thanks

*by 3 phase DC I of course me rectified 3 phase

240 V / 10 A = 24 ohms.
At 30 V and 24 ohms you get 30/24 = 1.25 Amps

30 V * 1.25 A = 37.5 watts

Probably not what you had in mind.

 

[stu]

No it isn't. But thanks. (still shaking my head as to why I didn't use ohms
law myself... must be getting old)

On the right track though... you just need more of them, i.e. 2 in
parallel = 75 watts, 4 in parallel = 150 watts, etc...- Hide quoted text -

If the elements on the new water heaters are like the one on my old water
heater, it would be pretty easy to tap into it in 6+ places. I'll look into
it.


How much power do you have to put into the water? A string of power
resistors around the tank under the insulation might do it.

Well I have tested it to 200W, around 500W should be possible.

Thanks again guys, I'll look into modifying the element.

 

[Cydrome Leader]

240 V / 10 A = 24 ohms.
At 30 V and 24 ohms you get 30/24 = 1.25 Amps

30 V * 1.25 A = 37.5 watts

Probably not what you had in mind.

a steel rod (even threaded) can be used as a giant low ohm resisitor.

 

[RW Salnick]

Cydrome Leader brought forth on stone tablets:

a steel rod (even threaded) can be used as a giant low ohm resisitor.

If the heating element has a resistance such that it will pass 10 amps
when 240 V is applied across it, then when 30 V is applied across it,
1.25 amps will flow through it.

bob

 

[[email protected]]

| Cydrome Leader brought forth on stone tablets:
|>
|>>stu wrote:
|>>
|>>
|>>>I want to use the element in a hot water heater as a dump load. If the
|>>>element is 240VAC 2400W and I am dumping 30V 3 phase DC, am I limited to
|>>>the current of the element at 240V? 2400/240=10A?
|>>>Thanks
|>>>
|>>>*by 3 phase DC I of course me rectified 3 phase
|>>>
|>>>
|>>
|>>
|>>240 V / 10 A = 24 ohms.
|>>At 30 V and 24 ohms you get 30/24 = 1.25 Amps
|>>
|>>30 V * 1.25 A = 37.5 watts
|>>
|>>Probably not what you had in mind.
|>
|>
|> a steel rod (even threaded) can be used as a giant low ohm resisitor.
|
| If the heating element has a resistance such that it will pass 10 amps
| when 240 V is applied across it, then when 30 V is applied across it,
| 1.25 amps will flow through it.

But in terms of watts, this goes from 2400 down to just 37.5.