Reducing voltage

[Petemate]

Hi Everyone.
A customer of mine has a house sewerage system which includes an aeration pump. It is only low wattage - maybe 50 watts and rated at 220 to 240 volts.
However it keeps cutting out after about 20 minutes due to an internal thermal switch. The unit is brand new.
When I measured the supply voltage, it is 257 volts. The local authority in Cyprus won't reduce the voltage unless it is above 260 volts.
What is the cheapest way to reduce the voltage to the pump. I was thinking about a dimmer switch, but does this reduce the voltage or just clip the waveform. Suggestions please.

 

[radiohead]

Google Voltage optimiser

 

[Pete999]

Hi Everyone.
A customer of mine has a house sewerage system which includes an aeration pump. It is only low wattage - maybe 50 watts and rated at 220 to 240 volts.
However it keeps cutting out after about 20 minutes due to an internal thermal switch. The unit is brand new.
When I measured the supply voltage, it is 257 volts. The local authority in Cyprus won't reduce the voltage unless it is above 260 volts.
What is the cheapest way to reduce the voltage to the pump. I was thinking about a dimmer switch, but does this reduce the voltage or just clip the waveform. Suggestions please.

Voltage opimiser to limit voltage output to equipment and keep it constant at required limit. Plenty of suppliers I used them to with sucsess. Just tell them the parameter you require, job done.

 

[freddo]

Voltage optimiser is rather expensive, the cheapest option for such a small load would be a small 'buck' transformer. (search online)

 

[Pete999]

Voltage optimiser is rather expensive, the cheapest option for such a small load would be a small 'buck' transformer. (search online)

Depends on the equipment and what you require at the end terminals?

 

[freddo]

I assumed it was to be permanently connected and only supplying the aeration pump.

 

[Pete999]

I assumed it was to be permanently connected and only supplying the aeration pump.

Agree, but you need something that is reactive to voltage fluctuation, not having used Buck TXes are they reactive can they be left to their own devices?

 

[freddo]

A buck transformer will drop the supply voltage by the winding voltage, there is no automatic control. As the pump is ok at 220-240V I wouldn't worry if the supply dropped a bit. a 24V transformer would drop the current voltage to 233V well within the pumps rating.

 

[Pete999]

A buck transformer will drop the supply voltage by the winding voltage, there is no automatic control. As the pump is ok at 220-240V I wouldn't worry if the supply dropped a bit. a 24V transformer would drop the current voltage to 233V well within the pumps rating.

Like I said depends on the vagaries of the needs of the load really, but it is another option to be considered. At least with the VO it cn be left to optimise the output with regard to the fluctuating inpu, and the firm I used provided excellent Customer care, and after sales, sorry been a while and I can't recall the Firms name.

 

[pc1966]

It appears that CEF sell one for £361 (inc VAT, part MCG63ES2) but I doubt you would see that in electricity savings. However, if your high supply voltage is causing problems then you might see some benefit in reliability, etc., in the property as a whole to justify the cost.

 

[David Prosser]

Is it an air lift pump or is it providing aeration to reduce septicity ? Just wondering as it may be cheaper to provide a more robust/electrically forgiving unit rather than trying to rectify the voltage issue.

 

[marconi]

https://cpc.farnell.com/ducati/4-16-10-08-14/capacitor-5uf-450vac-lead/dp/CA05803

Put a 5uF 450V ac motor run capacitor in series with the motor.

Required voltage across motor is 240V. Power is 50W. Ignore efficiency and PF.

Effective resistance of motor is 240 x 240/50 = 1150 Ohms = R

Current through motor is 240/1150 = 0.2A so when R and reactance X are in series across 260V supply required impedance Z is to be 260/0.2 = 1300 Ohms.

Zsqd = Rsqd + X sqd ==> 1300 x 1300 = (1150 x 1150) + X sqd.

Thus X = 600 Ohms = 1/(2pi f C) ===> C = 5uF for 50Hz 260V supply to drop 240V across motor .

 

[Paul L]

Impressive applied knowledge there from Marconi, always good to look for lateral solutions

 

[Megawatt]

Hi Everyone.
A customer of mine has a house sewerage system which includes an aeration pump. It is only low wattage - maybe 50 watts and rated at 220 to 240 volts.
However it keeps cutting out after about 20 minutes due to an internal thermal switch. The unit is brand new.
When I measured the supply voltage, it is 257 volts. The local authority in Cyprus won't reduce the voltage unless it is above 260 volts.
What is the cheapest way to reduce the voltage to the pump. I was thinking about a dimmer switch, but does this reduce the voltage or just clip the waveform. Suggestions please.

Petemate the internal thermal can be made closed. A lot of people don’t even use P1 and P2 they just tie them together and it won’t trip the motor. You already have short circuit and overload protection on the motor. Yes the do serve several applications like a way for programmers to use as inputs but they can be a nuisance, you have to add in the ambient temperature which could make the motor run hotter than usual. If it was me I would Tie them together

 

[EricMark]

I would use a transformer with tapping as an auto transformer.