Can someone help me with the identification of a component please.

Thread Starter

boydage

Joined Oct 7, 2016
65
After putting 400v into the input of a 230v inverter we managed to pop a fuse, and a few components on the secondary side of the power circuit. I am hoping someone can help me please and identify this component. Its not familila to me. It is sitting right next to the rectifier SBR3508. Please take a look if you dont mind? Its popped the top half off which was lost.

Thanks in advance. Boydage
 

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ebp

Joined Feb 8, 2018
2,332
Judging by the color and the heavy leads, it is probably a negative temperature coefficient (NTC) thermistor. They are often used to limit "inrush" current where large capacitors are charged from a source that can deliver high current. The resistance is "high" (usually still just a few ohms to tens of ohms) when cold and drops when it heats up due to current through it. Unfortunately, they are available in a rather large range of current ratings and resistances and there is no standard for part numbers.
 

pfofit

Joined Nov 29, 2006
57
Data sheet link that may be what you have . http://www.uei.com.tw/psp.pdf taken from website http://www.uei.com.tw/eproduct1.htm
The inked portion blown away is the diameter size. Measure the diameter of what is left and use the datasheet to figure it out.
Since it was zapped with 400 then you most probably have more damage elsewhere depending on how fast that thermistor bit the dust or rather "became" dust.
Have a pic of the rest of the circuit?
Cheers
 

Thread Starter

boydage

Joined Oct 7, 2016
65
I guess if I was a fly on the wall when it happened I would be laughing my wings off.

The story - a new three phase machine. Sent by the factory not realising production voltage 230v is 400v between phases. So the electrical inspector had just made the 3p installation in my workshop live and was still there when we plugged in the machine. The control circuit was 110v through a transformer but the inverter was supplied straight line voltage.

It went bang very quickly. In fact popped the new pole fuses out on the street, so mr inspector was out with his ladder again and replacing the pole fuses. The component I have removed is a direct short now....

I have attached a picture of the board. The two main caps have bulged. I guess if it was a thermistor it did its job! The original unit is being replaced but I am keen to pop in a couple of dollars worth of capacitors and obvious components to see if this unit can be salvaged.

Thanks for the info I will take a look now.
 

pfofit

Joined Nov 29, 2006
57
Wow, nice story, ha.
Besides the bridge, what else is on the back side?
What is the reverse voltage rating of that bridge? Part #?
Always laugh when i see "Elite" capacitors.
 

dendad

Joined Feb 20, 2016
3,002
Check the bridge and the FET(s) too. Make sure you get 2 good caps for replacements.
 
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