3 phase motor Question

[Ross1]

Evening Guys,

A commercial customer of mine has asked me to price a manual and a programmable speed controller for an existing ventilation motor. At the moment the motor is started and stopped manually.

I have no expertise in this area so some advice would be greatly appreciated.

The motor is 3 phase and is 15kW.

Thanks

 

[Darkwood]

This would be a mine field for anyone not experienced tbh, it could be a simple task circumstances depending or it could need very careful design and programming if at all possible that the setup could accept a VSD.

What kind of ventilation motor are we talking here, if its inline ducting then changing the speed could overload the motor as airflow, fan speed, duct length and design are carefully calculated.

 

[Ross1]

Thanks Darkwood,

its not an inline motor. If I contact the manufacturer they should be able to advise me I'm sure.

 

[Spoon]

Has the customer given you a spec on what he means by 'Programmable'? The possibilities are endless. Does he want to use a HMI for instance ( way OTT for this application but you never know what the customer is thinking) or just a pot? It's hard to quote for something if you don't know what you need to control the motor.

 

[Ross1]

He wants to be able to run the motor slower during peak times and program it to run at full capacity off peak Spoon

 

[Spoon]

He wants to be able to run the motor slower during peak times and program it to run at full capacity off peak Spoon

Sorry OP. Can you clarify 'peak times' please. Is it production at full pelt or a certain time of day?

 

[Ross1]

Basically wants the option of controlling the speed during normal working hours and if possible to program the motor to run at full speed when leccy is cheap

 

[davesparks]

What in earth is it ventilating that needs to run at full pelt outside of working hours?

 

[Ross1]

It's extracting particles in the air of the production shop

 

[Spoon]

so are we talking a VSD with a pot for the manual variable speed and a timer for the full speed?

 

[UKMeterman]

Someone needs to point out the fan needs to be run fast enough to maintain air quality... Cost is secondary.

 

[davesparks]

It's extracting particles in the air of the production shop

Then surely it needs to run at full speed when production is at full capacity?

 

[ElectroChem]

Forgive a stupid question, but isn't peak production going to be when you have the most particle generation and hence the greatest need for extraction? If anything, you want your vent running full pelt for a while after end-of-shift then spinning down overnight.

 

[Spoon]

Then surely it needs to run at full speed when production is at full capacity?

Hence my question in post #6

 

[Spoon]

Forgive a stupid question, but isn't peak production going to be when you have the most particle generation and hence the greatest need for extraction? If anything, you want your vent running full pelt for a while after end-of-shift then spinning down overnight.

You would have thought so. (Don't you just hate it when you think logically....) Looks like the customer has other ideas.

 

[Marvo]

Is there an air handing unit with element filters or HEPA filters to remove the particulates/dust? If so usually you'd install a flow sensor (or pressure sensor) linked to a VFD so as the filters become higher resistance as they become blocked the fan speed is automatically increase to compensate for the higher static pressures thereby maintaining a constant air volume through the system.

Never heard of a extraction system that's speed controlled according to the electricity tariff price.... sounds like accountants are going off-piste into engineers territory to me.

 

[Spoon]

Never heard of a extraction system that's speed controlled according to the electricity tariff price.... sounds like accountants are going off-piste into engineers territory to me.

You are just not with the times Marvo. There is nothing better than gassing your employees to save some money..... Get with the plan mate...

 

[Besoeker]

Never heard of a extraction system that's speed controlled according to the electricity tariff price.... sounds like accountants are going off-piste into engineers territory to me.

I had the same thoughts about peak times.
Somewhat related, my previous company ( I retired a few months ago) has an accountant negotiating maintenance contracts that have been in place for decades. And screwing them up from what I hear.

Previously, my very able PA took care of all of that and much more besides. She retired a bit over a year ago. Now they have no fewer than six people involved including the UK finance director and making an utter balls of it. It's a cast iron certainty that they will lose that business. Don't shaft the customers or they will vote with their feet.

 

[SheffSimon]

Evening Guys,

A commercial customer of mine has asked me to price a manual and a programmable speed controller for an existing ventilation motor. At the moment the motor is started and stopped manually.

I have no expertise in this area so some advice would be greatly appreciated.

The motor is 3 phase and is 15kW.

Thanks

My advice would be to decline to quote, and suggest they contact a HVAC company.

 

[Marvo]

I had the same thoughts about peak times.
Somewhat related, my previous company ( I retired a few months ago) has an accountant negotiating maintenance contracts that have been in place for decades. And screwing them up from what I hear.

Previously, my very able PA took care of all of that and much more besides. She retired a bit over a year ago. Now they have no fewer than six people involved including the UK finance director and making an utter balls of it. It's a cast iron certainty that they will lose that business. Don't shaft the customers or they will vote with their feet.

Yeah, I come across it regularly where accountants are involved in things they should be nowhere near, the result is usually a large short term saving which results in big bonuses all round but leaves a house of cards in the long term that ends up in ruins a year or two later costing an absolute fortune.