Online assistance for electrical trade people in New Zealand and Australia Login  |  Register  |   Forgot Password
Assistance for electrical trade people




Click here to send Forum Admin a pdf document for publication on this Topic

Documents must be less than 200k in pdf format

Posted By Topic: What is this component?

Jul 10 2018 19:35

Hi all
Just wondered what this component is in the picture. My guess is simply a relay however it is switching a 6A motor (white wire) and thought it might be a thermal overload device as there’s no obvious neutral. Certainly doesn’t look like it though. Single phase supply (red wire). Cheers
Picture in next post, have to reduce the size...

Jul 10 2018 19:39


Hopefully this works!

Jul 10 2018 20:53

What is it on?

Looks like a traic on a a Compac Fuel pump.

Jul 10 2018 21:35

There may be a code printed under the part on the PCB. Pump that into Google.

Jul 10 2018 21:40

Looks like a thermal cutout to me. Very similar to the type commonly found in modern ovens etc.

Jul 10 2018 21:56

If it is mounted on a heat sink I am going to say it is a thermal switch.

Jul 10 2018 22:46

Yeah, that number on the PCB is a big giveaway. BTA40 is common triac.

The yellow wire must also be connected to it.

Jul 10 2018 22:47

BTA40 Triac as printed on the PCB

Jul 10 2018 22:49

Beaten by a whisker by evanh

Jul 10 2018 22:51

Local supplier:

Jul 11 2018 21:21

...and the winner is...Fuel1 for the right part... and model :)
Thanks all for your comments.
So would it be used for current limitation/speed control of the motor? Or just a solid state method of switching the motor?

Jul 12 2018 00:50

From 50 Hz AC, it could provide speed control of induction motors, universals or even sloppy brushed DC. Quote from page one of the datasheet:
On/off function in static relays, heating
regulation, induction motor starting circuits

Phase control operations in light dimmers,
motor speed controllers, and similar

Has all four quadrants triggerable so can do 100 Hz switching with simplest non-rectifying circuit. aka dimmer circuit.


Jul 12 2018 01:04

It could just be a non-wearing on-off switch.

Or it could be a soft-starter with quick ramp-up to 100%.


Jul 12 2018 06:48

The traic are used to switch the motor on and off in the Compac C3000 or C4000 boards, no speed control as the pump has internal bypass built in to them. Should just be able to replace the traic or there might be a spare on the board depending on the unit.