Control wiring

[ktmtragic]

I have looked after a customer for several years who has a blast freezer and several cool rooms. The work carried out by the previous owner was poor. (this is an understatement) My background is electrical / industrial breakdowns. I have been asked on many ocassions to help the fridge mechanics out. I have a basic understanding of the concepts. The customer is relocating and so I have been asked to look after the electrical side. I get the impression the refigiration company is unwilling to supply wiring diagrams even though they are happy for me to do the work. I feel that the old adage knowledge is power applies here. By there not being any litrature they are able to hold the customer to ransome into the future.
Finally my question is are there any generic wiring diagrams that you guys use all the time for direct on line or star delta control wiring that I can adapt to suit each application or situation.
Thanks in advance George

[nike123]

Every compressor manufacturer in its instalation manuals gives such diagrams.

[Yuri B.]

Hello Ktmtragic.
There are three or four standard schemes. All is very simple, you probably have not dealed till now with starting 3 phase motors, but there is nothing special. Poles and the hint to starting mode is always on the inner wall of the contact box's lid (sometimes just a piece of paper stuck to, get sometimes lost). With Internet no problem whatsoever.

[ktmtragic]

Thanks for the info I understand that each compressor may be wired differently. What I have found in the past that they can get quite complicated when it gets to thermistors and oil pressure sensors etc. All I am after is a drawing of each type of starting method in it's most basic form
Cheers George

[Yuri B.]

http://samplecode.rockwellautomation.com/idc/groups/literature/documents/wp/mot-wp003_-en-p.pdf

So, Google smt like "motor starting methods" .

[Peter_1]

Oil pressure switch , thermistors, Kriwan, HP; LP eventually with reset, shortcycle prevention... are all protections for the startup method you want to use.
Different applications requires different startups and safety controls
You have different types of Kriwan and OPS's,
You can start your motor in PW or Star/Delta (depends on motor type), unloaded, capacity control, ...
I should look once to the documents provided on the Bitzer website www.bitzer.de You will find there a lot of schematics.

[ktmtragic]

Thanks guys for the replys Peter 1 sent me to where I wanted to be thanks again