Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 07-22-2012, 09:52 PM   #31
Member
 
Join Date: Jul 2012
Posts: 64
Rewards Points: 75
Default

Generator AC unit


is there any way i can make my own hard start kit for a 1,5 ton ac ?

quanchai is offline   Reply With Quote
Old 07-23-2012, 07:50 AM   #32
Master Electrician
 
Join Date: Nov 2008
Location: Northern Virginia
Posts: 511
Rewards Points: 284
Default

Generator AC unit


Quote:
Originally Posted by quanchai View Post
Magnetic relays it's made to transfer the power betwin 3 power sources, It does around 20 transfers a day has been working for 2 years now without a single problem

I can take a picture of it an show you ?
If by magnetic relays, you mean contactors, you could have a problem down the road. Contactors work fine for many cycles, but one of their failure modes is welding the contacts closed. This is caused by the repeated arcing at the contacts destroying the silver plating on the contacts. If contacts fail closed, you may get some spectacular or even dangerous/deadly results.

For the record, some cheaply made commercial transfer switches use contactors, but they are for optional generators and probably only switch a few hundred cycles in their entire useful life.

Mark
__________________
Licensed Master Electrician
Commonwealth of Virginia
busman is offline   Reply With Quote
Old 07-23-2012, 08:33 AM   #33
Member
 
Join Date: Jul 2012
Posts: 64
Rewards Points: 75
Default

Generator AC unit


You are right but the type i have been using for the last two years works perfect with around 60 amps load at all time
quanchai is offline   Reply With Quote
Old 07-24-2012, 03:12 PM   #34
Member
 
Join Date: Jul 2008
Location: NW of D.C.
Posts: 5,990
Rewards Points: 2,000
Default

Generator AC unit


Quote:
Originally Posted by quanchai View Post
i have been using for the last two years works perfect with around 60 amps load at all time
It's right censored data; you'd know more about its reliability if it failed once in a while.

Just make sure the contacts are rated for a motor load and that you fuse the lines in the event the relay fails.
Yoyizit is offline   Reply With Quote
Old 07-24-2012, 05:21 PM   #35
Member
 
Join Date: Jul 2012
Posts: 64
Rewards Points: 75
Default

Generator AC unit


Can you recommend some thing better like how about solid state relays ?
quanchai is offline   Reply With Quote
Old 07-26-2012, 01:01 PM   #36
Member
 
Join Date: Jul 2008
Location: NW of D.C.
Posts: 5,990
Rewards Points: 2,000
Default

Generator AC unit


Quote:
Originally Posted by quanchai View Post
Can you recommend some thing better like how about solid state relays ?
I'd stay with electromechanical but there is a way to monitor the life of your relay contacts.

At rated current, good contacts measure less than 30 mV and bad contacts come in at more than 100 mV. Possibly if you're running at half rated current, the values would be 15 mV and 50 mV.

Had a HO with flaky HVAC blower performance and it was working when I was there but the relay contacts came in right at 100 mV.
Took a chance, replaced the relay, everybody lived happily ever after.
Yoyizit is offline   Reply With Quote
Old 07-26-2012, 04:45 PM   #37
Member
 
Join Date: Jul 2012
Posts: 64
Rewards Points: 75
Default

Generator AC unit


But is sold relays not better

They dont have any moving parts
quanchai is offline   Reply With Quote
Old 07-26-2012, 04:47 PM   #38
Member
 
Join Date: Jul 2012
Posts: 64
Rewards Points: 75
Default

Generator AC unit


Sold State relays does also com in 100 amps
quanchai is offline   Reply With Quote
Old 07-26-2012, 04:54 PM   #39
Member
 
Join Date: Jul 2008
Location: NW of D.C.
Posts: 5,990
Rewards Points: 2,000
Default

Generator AC unit


Dunno'.

Compare cost vs. MTBF for both types. And for EM relays sometimes you can replace only the contacts in the case of failure.
Yoyizit is offline   Reply With Quote
Old 07-26-2012, 05:01 PM   #40
Member
 
Join Date: Jul 2012
Posts: 64
Rewards Points: 75
Default

Generator AC unit


i think using a timer with the contactor would be better because there would not be any instant switching
quanchai is offline   Reply With Quote
Old 07-26-2012, 08:51 PM   #41
Member
 
Join Date: Jul 2012
Posts: 64
Rewards Points: 75
Default

Generator AC unit


Could you please explain more about how to moitor the life of the relay ?
quanchai is offline   Reply With Quote
Old 07-27-2012, 09:43 AM   #42
Member
 
Join Date: Jul 2008
Location: NW of D.C.
Posts: 5,990
Rewards Points: 2,000
Default

Generator AC unit


Find a tech library and get books on electrical testing.

Yoyizit is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Ruud Pack unit "KABOOMS" upon First Light Up of the Day! Wirenut2tite HVAC 18 12-15-2012 11:11 AM
Had an Aire-Flo AC installed, looking for opinions mikemcd HVAC 14 08-01-2011 05:07 AM
new r-410a ac unit installation procedure(w/old unit r-22)? excalibur1 HVAC 0 06-06-2011 04:47 PM
Window A/C Unit and Supplying Power JayEnder Electrical 1 04-30-2011 08:50 PM
Inside Unit Runs, Outside Unit Runs (with help) no cold air beakon20 HVAC 4 08-13-2008 10:33 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.