VSP dropping RPM

[pickardc]

I have a Hayward VSP that not matter what speed it runs at will drop RPM for a second every few min or so and then go right back to full speed. Its enough if a drop to cause the Heater to report low flow and occasionally the flow sensor as well. I checked the voltage come into the pump and its solid 120V and never drops. I saw no drop in LV single as well. For the life of me I can't find any reason for this to be happening. Grounding is all tight as well. Its on the same circuit as the heater but it does this with and without the heater running.

 

[mas985]

What is the model# of the pump?

 

[pickardc]

What is the model# of the pump?

HL2350020VSP

 

[JamesW]

I checked the voltage come into the pump and its solid 120V and never drops.

Does the motor label specify 115 or 230 volts?

 

[pickardc]

230

 

[JamesW]

If you're measuring 120 volts and the motor specifies 230 volts, you have the wrong voltage supply.

 

[pickardc]

its 115 on each leg. so 230 total.

 

[wireform]

Possibility a bad or a lose connection on one of the legs would be the first place to check. Also check L1 to L2. Amp it out while its doing this and watch for ant fluctuations.

 

[mas985]

That pump and I think most VS pump has alarms if the voltage is more than 10% out of spec so I don't think it would be a voltage issue. If the temperature is too warm or the pump is overloaded it should alarm as well.

Sounds more like it is a control board issue. Is this pump being operated in stand alone mode or via an external controller?

 

[pickardc]

Its controlled by an OmniLogic controller. Its very odd it runs norma and then randomly drops the rpms for a split second then right back up. There is no pattern to the drop but happens frequently and at any speed.

 

[mas985]

Is it frequent enough to capture the actual RPM change?

 

[pickardc]

I have no place to see that as it doesn't show on the OmniLogic. Its enough of a drop to trip the pressure sensor on the heater.

 

[JamesW]

Possibly a voltage drop. I would monitor the voltage to see if it drops during the rpm change.

 

[mas985]

That pump, as do most VS pumps, have alarms for voltage drop so I don't think that would be the problem. Plus a change in voltage does not change the RPM in a VFD.

 

[JamesW]

If the voltage dropped enough to hit an amp limit, some motors reduce the rpm.

If the Superflo VS is wired to 120 volts, it will limit the rpm such that the amp limit is not exceeded.

I agree on the low voltage causing an alarm.

However, I would still check the voltage to see if it's doing anything unusual.

The voltage might be dropping some, but not enough to trigger an alarm depending on what the alarm trigger point is.

 

[pickardc]

Checked both the amp draw and the voltage. Volts reading 244-245 amps 21-22 on each leg. Nothing major and the pump didn't drop RPM when there was the =-1 V or =-1 1 amp Its a maxflo 500 Hayward Pump

 

[JamesW]

21 to 22 amps?

There's no way. That's 5,280 watts.

What does the motor label specify for amps?

You need to be looking at the voltage when the rpm drops.

 

[pickardc]

when the Motor drops there is no change in the voltage

 

[JamesW]

How are you testing the amps. 21 to 22 amps is highly unlikely.

The manual says 10 amps maximum.

 

[pickardc]

amp meter on each leg at the breaker in sub panel just for the pump. Its on a 20amp 2 pole breaker