staring circuits / run capicator

[Jeff Cox]

Hi everyone
All the best for the new year and lets hope for some hot weather .
My names Jeff I have been installing slits for 10 to 15 years now and some times have been called on to service a non functioning unit here and there .
So as Ive been in the trade for 35years or so felt it was way past my time to understand starting circuits a little better.
Q. Why do the Caps blow so often and
Q. whats there general use in the circuit and
Q. whats the best way to understand the start/run circuitry

Thanks guys

[wambat]

go here: http://fridgeman.wordpress.com/2008/...its-part-1/and part 2

[nike123]

That link doesnt work!
This is right one:
http://fridgeman.wordpress.com/2008/...rcuits-part-1/

Also, study this manual:
http://www.embraco.com.br/portugue/produtos/MP01EG.pdf

[Grizzly]

Welcome to the forum Jeff.
Have a look at the attached it has some useful info.
If I can find more i will post it.
Cheers Grizzly

[Grizzly]

Hi Jeff.
I promised I would add to the list of available Info!
Try the link below as it is a website
STUFFED with lots of free motor info.
Some of it very interesting.
cheers Grizzly

http://www.lmphotonics.com/

[josef]

Good work Grizzly

[coolments]

Hi Jeff

I put some info on capacitors in an earlier post, it may help you also, see link below.

http://www.refrigeration-engineer.co...051#post101051

[brunstar]

start and run capacitors are used in a circuit as when a compressor starts it need the high current and high torque to get going, the capacitor will store the voltage and release it at a peak giving the motor a higher torque to start from a stationary position.
Once it starts speeding up it no longer needs a lot of torque so the windings switch over to a low torque and low current operation, this is also the same principal why we use star delta starters on large motors.
i hope this can be of help.

[paul_h]

There's Capacitor Start Induction Run (CSIR), similar to a star delta 3 phase system I guess.
There's also capacitor start, capacitor run, so there's a capcitor in the run circuit that's alway energized too.

But in air conditioning the usual setup is Permanent Split Capacitor (PSC) where the capacitor and start winding is always energized. Even though they on the 'start' winding, they are called 'run' capacitors, the run winding has no capacitor.

I have never replaced so many capacitors in my life, doing 1-2 every day!
When I worked for a company mainly repairing big brands, I maybe did 1 a week. Now I'm doing all sorts of brands including the cheapies, there's so many to replace.
Easiest money in the world though, about the simplest repair you can do for an a/c 15min job, callout out fee and parts % markup.
A lot easier than replacing fan motors, compressors or repairing leaks!

edit: there's also soft start systems that have a normal 'start' capacitor as a PSC system, but also have another 60+uF capacitor for the soft starter start circuit which gets activated by a relay.
BTW it's normally heat or poor manufacturing quality* that evenutally kills them, I've never had to replace one in winter even though all these units are working in reverse cycle heat mode all season.
*as I said, main big brands capacitors lasted 4 years+ average 6 years, cheap brands capacitors last 2-4 years max.