Ascon ac multi split

[mike live]

having problem with an ascon multi split system. just wondering if any one has worked on these units. i have previously fitted a multi plits system in the past 2 months . I'm now having problems with the contactor of the compressor chattering. would like to know if any one else has come across an other problems and how they were resolved

[frank]

A contactor / relay chattering is normally cause by low voltage across the coil. The coil has a threshold below which the coil will not hold 'in'.
Check you control circuit from start origin and look out for a major volt drop.

[mike live]

May now think that the contactor coil is 400v (across A1 and A2 ). this would link up with what frank has said about the major voltage drop. would this cause the chattering or would the contacor not pull anyway. One thing i have tried that seem to reslove the chattering was to re wire the crank case heater . the crank case heater took its live from an normally closed side of the contactor , (linked across from one of the 3 phase supplies) and ended its neutral on the same pole as the neutral for the signal for the contactor( A2). i rewired the crank case heater directly to the neutral block of the unit. my question is would the normally closed pole of the contactor that feeds the cch interupt the neutral of the contactor coil and cause it to chatter.

[frank]

How can you have a 400v contactor coil if you have neutral on A2?

[mike live]

would it be possible if the manufactuer had put on 400v coil contactor by mistake that this would create the chattering being experience or would the contactor not pull

[mike live]

the contactor not pull in

sorry

[frank]

would it be possible if the manufactuer had put on 400v coil contactor by mistake that this would create the chattering being experience or would the contactor not pull
Quite possibly Mike - has the unit run before or are you trying to commission it?

[frank]

You don't need to post twice Mike. If you have made a mistake or forgotten to add something then just click on the EDIT button and SAVE the changes :)

[mike live]

the twin split system has been commission , and is running at present . the only time this system starts to recreate the chattering was when indoor evap (which has different power supply and the control relays for compressor, condersor fan motor and 4 way valve) was turned on befor the condensing unit. cheers frank just done that edit thing

[Brian_UK]

Are the indoor and outdoor units fed from the same phase?

There could be some interference getting to the control circuit.

[mike live]

not too sure . there is a three phase supply coming from one dis board for the power supply to the condensors, and a ring supply for the evaps coming off a different board . they had to be different boards as the supply to any equipment inside the buiulding had to go through a fire managment system.

if there was a difference in which phase was used for the contactor signal, in what way could this disturb the 240v signal.

The ascon unit has a 3 core interconect ( plus an earth ) that controls the operation of out door fan, 4 way valve and compressor . this 240 signal comes from indoor pc.

just found a modification diagram for a multi system will try to attach

[Andy W]

I have had equipment fed from different boards before and it does cause problems, we discussed it at night school many years ago when I did my then 15th edition and there was a reason behind it that I can not remember. I think a long term solution would be to run off the same board and not mix supplies.

[frank]

But did you check the voltages with a meter?

[Jase]

Check all electrical wiring for tightness.
Could possibly be loose wiring causing problem.

Jase

[mike live]

I have checked all wiring . does not seem to be a problem there . would also like to note that this has not justed happed to one unit . At least 2 more twin split systems have had this problem (2 units myself and a third with a different engineer) problem was iether resloved by disconnecting the neutral for the cch and turning power supply for the condersor befor the evap. will probably need to attach wiring diagrams so you can see what i'm working on . next time go to job will take photo evidence