Trouble shooting?

[FrankUK]

I do a lot of commissioning and trouble shooting for a well known name of ventilation/heat recovery equipment, and I was tasked to have a look at a problem in Bournemouth today, where the fault was reported as an electrical heater 'overheat' problem.

The ventilation unit has an inbuilt supply fan and extract fan, heat exchanger and electric heater battery. The unit is 3 phase with inbuilt controller.

Here's the pictures of what I found. The additional wire terminals (not the manufacturers grey ones) have been fitted by the installing electrician, who has taken a supply to feed the orange relay which switches the additional ventilation fans on when the unit is running.

K1 is the contactor for the supply fan on full speed

Anyone spot what has happened?

 

[KAS1]

is any of the armour flexes earthed?

 

[Stuuk1]

Taken the supply for the relay from the Star side of the star/delta timer.

When this switches over to delta the extra fans cut out leaving the other fans to overheat...

 

[lister101]

Beat me to it, must type faster

 

[FrankUK]

Yes, all sheathing earthed

- - - Updated - - -

 

[FrankUK]

Taken the supply for the relay from the Star side of the star/delta timer.

When this switches over to delta the extra fans cut out leaving the other fans to overheat...

Not even close.....

 

[Darkwood]

Are you asking us about your fault or all the other issues i can see ?

Overload protection for motors.
Screening on SY not earth (if carrying low voltage)
The complete mess of a job in the control box

 

[Stuuk1]

Why two feeds and a neutral to energise a single phase relay?

I'm trying to see where the second brown goes... It's marked U1 but disappears somewhere

 

[Stuuk1]

Are you asking us about your fault or all the other issues i can see ?

Overload protection for motors.
Screening on SY not earth (if carrying low voltage)
The complete mess of a job in the control box

The drawing asks for a 10a breaker and that's what is installed. The only thing I could see that could perhaps be different is that you may want a D type breaker if you have startup current of two fans but the size if the fans isn't states..

I'm stuck!

 

[Darkwood]

The motors require there own overload protection stuuk1 i was not refering to the 10amp mcb giving short circuit protection for the fans... how can it protect the fans from overload.

 

[FrankUK]

All overload protection is in place.

All wires, SY or other is correctly installed and earthed.

The problem being investigated was why the electric heater overheated, shutting the unit down on fault.

The manufacturers wiring has been altered by the installing electrician

The additional fan relay (orange one) has a trigger input (B1)

 

[Darkwood]

Right im with you well in that case unless the fan is on full speed the additional fans wont operate.... other than that its still poor workmanship... its just hard to jump between your write up and the picture which is just a mess of cables.

Its not too easy to spot has we have a partial wiring plan and we don't know how the set up works where-as you will be familiar with it, i would have needed a full wiring plan to work out how the system functioned to jump in quicker with an answer....

Either way the original control board including the dodgy additions is poor workmanship looks like it was made up by a domestic sparky out of his comfort zone

 

[itselectric]

the cables are not on the correct outgoing terminals of the contactos

 

[FrankUK]

I'll leave it a couple of days before I explain what has gone wrong, to give others not on line at the moment the chance to have a look at the information.

All the clues are there though.....

 

[ayjay]

the pics are crap

 

[benji]

are we seeing enough of the drawing to find the problem?

 

[Stuuk1]

Haha I love this kind of thing!

 

[Darkwood]

Im puzzled a bit as you say it was reported as an electric heater overheat which would suggest airflow loss, now this system should have air flow senses to shut heater off long before it overheats but thats another issue as i said i cant see the way the system works and thus not sure what and when which motors and heaters should be active and when not... its easy to see a fault if your familiar with how the system works in the first place. I feel the way you have presented the thread means we are probably overlooking the obvious but can you tell us how the system would normally work and what fans should be on or off when heater bank is needed?

All i see is if K1 or K2 are not closed then the orange relay cant pull in but again you supplied partial info and want us to pick the relevant parts of it.

 

[Darkwood]

Stuuk1 ..... what was your other post on about... where is the Star/Delta timer or even the set up for star delta?

 

[FrankUK]

Im puzzled a bit as you say it was reported as an electric heater overheat which would suggest airflow loss, now this system should have air flow senses to shut heater off long before it overheats but thats another issue as i said i cant see the way the system works and thus not sure what and when which motors and heaters should be active and when not... its easy to see a fault if your familiar with how the system works in the first place. I feel the way you have presented the thread means we are probably overlooking the obvious but can you tell us how the system would normally work and what fans should be on or off when heater bank is needed?

All i see is if K1 or K2 are not closed then the orange relay cant pull in but again you supplied partial info and want us to pick the relevant parts of it.

You are on the right track...you just need to look a little closer at the details posted....(K1)