Starting systems hermetic compr

[Peter_1]

Does someone knows a good manual, book, pdf, about the different starting systems of compressors: current relay, potential relay, start and run caps, units without current nor potential relay, only a start cap,...

Especially the starting systems from Unité Hermétique, Tecumseh, Aspera,...

For example, I have 2 different explanations about potential relays, cut in voltage and holding voltage of these relays,..

[NoNickName]

There are many type of starting: CSIR (capacitor start, induction run), CSR (capacitor start and run), CSCR (capacitor start, capacitor run).
Induction run uses amperometric relay, capacitor run uses voltmetric relay.
By using the above acronyms and terminology, there are different pages on the internet explaining the various starting methods.
I have some documents, but they are copyrighted material I used for trainings.

[Peter_1]

It was mainly the PSC starting method which bothers me most.
I would like to explain this starting-up from the magnetic field in the compressor why you need a start winding, why the motor doesn't know how to start when energizing,...
I would like to see how others approach this, starting from zero.
Knowing how something works is good but be able to explain this this easily is even better.

[Peter_1]

This is a good one but this explanation isn't starting from the beginning.
http://nanskill.go.th/air/data/Compressor-Motor-Types-and-Start-Relays.pdf

[Peter_1]

Perhaps others can benefit from my search, from page 199 till 217 http://www.scribd.com/doc/7268693/Electricity-for-HVAC-Techs

[Peter_1]

Potential relay,

Some say that the voltage over the potential relay coil will be 70% of the connected line voltage, some say that the generated voltage will add up to the line voltage.

Copy/paste from http://www.exchangor.com/csr_motor.shtml


# The operation of the potential starting relay is based on the increase in back electromotive force (back EMF) or a bucking voltage that is generated across the start winding as the motor increases in speed.
# The large metal mass of the motor's rotor turning at high speeds has a voltage generating effect. This generated back EMF opposes line voltage and can be measured across the start winding or across the coil of the potential relay at terminals 2 and 5.
# The back EMF is usually a higher voltage than the line voltage and can be in the 400-V range.
# All motors have different magnitudes of back EMF.
# The back EMF voltage generated across the start winding causes a small current to flow in the start winding and in the potential relay coil since they are in the same circuit.
# When the back EMF has built up to a high enough value, referred to as pick-up voltage, the contacts between terminals 1 and 2 will be picked-up opened.

[cool runings]

Does someone knows a good manual, book, pdf, about the different starting systems of compressors: current relay, potential relay, start and run caps, units without current nor potential relay, only a start cap,...

Especially the starting systems from Unité Hermétique, Tecumseh, Aspera,...

For example, I have 2 different explanations about potential relays, cut in voltage and holding voltage of these relays,..



From college days


Potential (or Voltage) Operated Relay

These Relays are used for Capacitor Start / Capacitor Run Motors only. The Relay coil is sensitive
to Voltage other than current and it is connected in Parallel with the Start Winding of the Motor.

The Voltage across the Start winding is small at switch on and increases progressively as the speed
increases to reach a maximum at normal running speed.

At switch on, current flows from the supply through the Run winding and also from the supply, through
the Start and Run capacitors, through the Start Winding. When the speed has increased enough, the
Relay pulls in (ie at its normal, preset, pull in voltage) its contact opens and the Start capacitor is
disconnected. This allows the Motor to continue to run with current passing directly to the Run Winding
and via the Run Capacitor, to the Start winding also.


coolrunnings

.

[Peter_1]

http://ww1.microchip.com/downloads/en/AppNotes/00887a.pdf

[Peter_1]

This one collects many papers http://www.educypedia.be/electronics/motoracsingle.htm

[Peter_1]

This is more what I was looking after
http://www.tcf.com/TCFBlower/pdfs/engr_data/ED1100.pdf

[Dan]

Hi, Peter. Great PDF. I wonder how to boil all that information down to something I can equip my techs with.

I read it perhaps too quickly, but I have long puzzled over voltage ratings and didn't see anything about that.

Also, I am puzzled that the wire thickness is less in a start winding than in the run windings. And I further wonder about hard start kit applications, which to me do not seem to add the capacitor function.

Good stuff. Well worth rereading. This has long been a puzzlement to me.

[Temprite]

Hi Peter.

This is a good book. I keep in the van.

[bill1983]

can ytou scan a couple of pages to show us, or tell us where to get it?