a/c fault

[Mark]

Hi all
Heres a easy question to answer
(the fault stemmed from installation)
Small paper shop two seperate ceiling suspended a/c units electrical supplied to outside c/u (single phase).Inside ahu fed via interconnecting cable.(single phase)Each a/c independantly controlled via controller.
The area suffers a power cut in storms ,power comes back on circuit breaker tripped on one unit customer resets breaker.
He then decides to switch one a/c off via controller.
What happend to a/c systems?

regards mark

[shogun7]

In comming line feeds both circuit breakers but line is too small for both units pulling LRA so the weakest CB trips is a possibility me thinks
cheers what

[Mark]

ok, the two a/cs functioned ok until one controller was turned off,



mark

[Peter_1]

One unit outside or bisplit?
Electonically controlled?

Otherwise, a gues... supplies switched, setting off one indoor unit but outside unit keeps cooling a non powered inside unit and freezes completely??

[Mark]

Hi peter

2 a/cs in papershop.

1x ahu fed by 1x c/u.
1x ahu fed by 1x c/u.

Both electronic no thrills hard wired controller for each system.

mark

[chemi-cool]

mark,


if the main switch was on and the guy swichd it off by the controller, so it went off.

chemi

[Mark]

ok ,I will elaborate i was asked by an engineer if i could attend site with him and find wiring fault?.

[chemi-cool]

its not common, but some times, un experianced tech's, connect one c/u of one ac to the other one's ahu.

I mean ofcours the controls.

chemi

[Mark]

Hi all

The two a/cs would work together cooling,heating .
When the circuit breaker tripped originally one ahu came back on and would not function normally,the manager manually reset circuit breaker and noticed the strange operation and consequently turned circuit breaker off .The engineer attended site tested reset circuit breaker both a/cs worked ,When the customer turned one unit off by controller both stopped heating (as per command from one controller) and shop ambient dropped.
I get a phone call can you attend a job to locate wiring fault get to site find out the cowboys who installed had crossed ahu feed from the condensing unit ummmm the units had worked like this since installed and had gone un-noticed.Lol


regards mark

[chemi-cool]

mark,

I saw something even worse.

I was called to look at a 20000 L milk tank that had cooling problems. it turned out that the cowboy (a compliment in this case) had crossed the suction and liquid line from two c/u!!

chemi