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does missing neutral line from a 3 phase source lead to problem in the device connected to it?

layana

New Member
hi,

A 3-phase AC(Air Conditioner) inverter training model connected to a 3-phase plug (plug 1) was working without any problem, but when the 3-phase plug changed to another one(plug 2) the model didn't work and the circuit breaker of the model went off and each time trying to run the model the same problem exist. then the model connected to plug 3 for one time and the same problem exist.

when the company from which the model was purchased came to check the problem , Electrician tell that the plug 2 L1,L2,L3 and E connected but N missing and source 3 L1,L2,L3 connected and N missing but E line connected to N of the 3-phase plug.



s.jpeg



when the control board of the module checked by the company they tell that the following component need to replace diode (rectifier) , capacitor and ipm module in inverter board.

ss.PNG



does missing the neutral or use E instead of N make this problem ?

which mainly damage the components connecting it to plug 2 or plug 3 ?

L
 

rjenkinsgb

Well-Known Member
Most Helpful Member
If the electronics use neutral as a reference, or run some parts from power between one phase and neutral, leaving out the neutral connection could easily cause it to not function and possibly cause severe damage.

Generally if a piece of equipment has a neutral, then it is essential & must be properly connected.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
You might also try mentioning what Country you are in, as your problems depend greatly on that.

In the UK Neutral is connected to Earth at the sub-station, so it 'should' work regardless of the neutral connection been connected to either Neutral or Earth - but I would seriously suggest that it SHOULD be connected correctly.

'Generally' with three phase in the UK there should be very little current carried in the Neutral connection, as one of the main points of three phase is that the phase loads should be fairly well balanced, and only the small unbalance current flows down the Neutral wire. For this reason three phase often has three thick live wires, and a thinner neutral.

But it sounds like you need some competent rewiring?.
 

tomizett

Active Member
Agreed with RJenkins. Not all equipment that runs on 3-phase is "really" 3-phase equipment - some or all of it may be tied between a live and neutral. If the neutral is not connected to the grid then it's voltage is only defined by the balance of the loads between the phases. Any imbalance in this current could be drawn through the neutral-connected load.

At a previous employer, we had a large batch of moving head lights damaged by a "dropped neutral" at a concert.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Agreed with RJenkins. Not all equipment that runs on 3-phase is "really" 3-phase equipment - some or all of it may be tied between a live and neutral. If the neutral is not connected to the grid then it's voltage is only defined by the balance of the loads between the phases. Any imbalance in this current could be drawn through the neutral-connected load.

At a previous employer, we had a large batch of moving head lights damaged by a "dropped neutral" at a concert.
Needless to say, that would likely be pretty catastrophic - but it wasn't really a three phase load at all - and for concert rigs (because of the HIGH power consumption) it's usual to specify a solid neutral from the power company. Losing neutral when using single phase loads on a three phase system could easily approach the full 415v across the least loaded phase :eek:
 

ronsimpson

Well-Known Member
Most Helpful Member
US appliances. It is typical for the heater coils and motor to run on 220 with out neutral but the clock and computer runs from line to neutral (110vac).
 

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