What Kind of Transistor?

Looks like some kind of MOSFET.

Does this help?

http://en.wikipedia.org/wiki/MOSFET

I was thinking it might be a MOSFET and even looked at that page on wiki earlier. I can't find any kind of reference to that symbol. Very strange. I was hoping to identify it so that I might understand the operation of the circuit. The circuit is for a windmill control circuit and the transistor is used in some sort of bridge rectifier circuit.

It's probably an IGBT (insulated gate bipolar transistor). Works like an FET driving a bipolar transistor, and they're a lot more rugged than MOSFET's.

Yes, it looks like an IGBT

The schematic should ID the transistor which is included/referenced in some type of BOM or parts list. If nothing , then identify its function in the ckt and the purpose of the contraption it is soldered to.

It can be an "N" channel MOSFET or a FET-Darlington (NPN bipolar transistor driven by a FET)

Looks like an IBGT but someone forgot to draw that little diagnal line in the middle.

I agree with that: if I had to design a symbol for an IGBT that's what I'd have done: here's a document which shows the symbol HGLDR is referring to:

http://www.onsemi.com/pub/Collateral/AN1541-D.PDF

Randall, Bill, PLM NY

I think, too, that it is the IGBT. The symbol is for the right hand side a BJT and for the base drive, the MOSFET.

Actually, from the link you gave:

When compared to BJTs, IGBTs have similar ratings in

terms of voltage and current. However, the presence of an

isolated gate in an IGBT makes it simpler to drive than a BJT.

Much Thanks Randall!!

That is a really handy app note which I saved for future reference.

Bill

why not understand how the base is being driven and work with that to find if it's a transistor device or not. that or measure the resistance between base and or the other two points.

BJT are driven with the base current. FET, IGBT are driven by voltage (if we do not consider the charging current of the base-emitter junction (I have used the pin names from BJT). Look for data sheet for the transistor you have in hand, and there you will find what you need to make it work.

http://www.allaboutcircuits.com/vol_5/chpt_9/15.html

Thanks for all of the input. I sure do appreciate it. It appears that the device is an IGBT. The application note was extremely helpful. The device is used on the control circuit for a wind turbine and is indeed a power application. It looks from the schematic like it "senses" the output voltage from each phase and manipulates the output of the rectifier accordingly. now that I know what it is, I can figure out how the circuit works.

Thanks again,

DAG

Yes, this is N-channel IGBT.
Mostly its using for voltage over 300 V, at lower voltage it has a good competitor – CoolMOS or Superjunction MOSFET.

It is an insulated base transistor. I've only seen this once in my life.