help please

[hakan]

l have attached a picture of resistor or a diode picture can any body help me what is this and where can l find it? its been used on heating element 1200kw it drops the voltage 240v ac to 136v ac .cheers

 

[(*steve*)]

Looks like some form of PTC device.

Without something for scale, I really have no idea how large it is, but I suspect it's pretty large.

Are there part numbers on it? Was it on a board (and are there any part numbers on that?)

I can't imagine it drops the AC voltage as you state because if it did it would be generating almost as much heat as the heating element!

 

[davenn]

Looks like some form of PTC device..........

yup, or the other choice that crossed my mind was an old style power diode

Dave

 

[shrtrnd]

It's a input power surge arrestor, pretty common in 1980's gear.
What did it come out of?

 

[hakan]

no part number on it no other parts has been used otherthan heating element and it does get very hot , its been used on doner machine . Thank you for your help guys l need this item asap.

 

[shrtrnd]

Look, I've never seen one go bad that didn't have visible physical damage to it.
Is that lead separated from the device?
What makes you think it needs to be replaced?

 

[hakan]

there is 4 heating elements no other devices each element has got 2 of does items on it. one of them is blown, this one on the picture when l measure with my meter it gives 240 vac out others are 136vac on output

 

[shrtrnd]

I'm tied-up with my own problems right now.
I don't know anybody that makes them looking like that anymore, they're all
encapsulated now, so when they blow-up, the pieces stay together.
What you're looking for a transient voltage suppressor, or surge suppressor.
Google them.
All it does is prevent a big voltage spike from the power line to the device, apparently
a heater in your case. when power is first applied to the equipment.
You look for the device on Google, find out who makes them, used to be mostly
GE, but Matsushita (Panasonic) and a few other companies are big into them now.
Then find the voltage range you need.
REMEMBER, these devices are designed for the PEAK volttage applied to the circuit,
Not the RMS, or what most voltmeters read in now.
You're trying to keep the input voltage spike from damaging your equipment.
Sorry I can't be more helpful, but I gotta go, ....

 

[hakan]

Shrtrnd thank you for your time mate.

 

[(*steve*)]

What's the mains voltage where you are hakan, and where (city, country) do you live. I'll try to find an appropriate component and tell you where you can order it from.

 

[hakan]

thanky you Steve I ive in leicester ,main is 240v ac

 

[gorgon]

Without a schematics it is hard to know, but since the device is reducing the voltage to about the half on a meter, I would think it is a diode. Rectifying the AC gives about half the effective voltage, and effect. The only way to be certain is to take a look with an oscilloscope to see the before and after effect of the device.

TOK

 

[(*steve*)]

thanky you Steve I ive in leicester ,main is 240v ac

Thanks

Without a schematics it is hard to know, but since the device is reducing the voltage to about the half on a meter, I would think it is a diode

OK, the original description was that it was in series, but later suggestions were for devices in parallel.

I wonder, does it by any chance have a switch across it to change from Low to High?

 

[(*steve*)]

If the device is a diode (and we're not absolutely sure yet) then you could try maplin for a "P600J" which is a 6A 600V diode.

We also need to know what the power this device is rated at to ensure that this is an appropriate part.

edit: you said 1200kW, I presume 1200W. If so it's 5A which is uncomfortably close to 6A, but since the load is likely resistive, you should squeak in.

 

[gorgon]

OK, the original description was that it was in series, but later suggestions were for devices in parallel.

I wonder, does it by any chance have a switch across it to change from Low to High?

I would think that the parallel 'variant' is with a switch, for high/ low switching.

If it is parallel over the load, it should short it out, and break the fuse, if faulty. If in series , and faulty(shorted) the heat would be on high permanently, as described.
If a diode I would use a 10 or 16A version, for the higher inrush current at startup.

TOK

 

[(*steve*)]

I would think that the parallel 'variant' is with a switch, for high/ low switching.

If it's in parallel it's most likely a varistor or something similar.

Picking the wrong device could be spectacular (in a bad way)

I agree about the current rating. This was the highest current diode that maplins seem to stock (in an appropriate voltage). Maplins are the UK version of Tandy? (That's my impression)

Farnel (Element 14) or RS are two other options but you're likely going to be up for a shipping charge (although there will be no problems getting a higher current device).