LavenburgElectric
Electrical
- Jul 12, 2009
- 1
Is there a way to verify the oprating voltage of a pump motor that is inaccesible. The power sorce has been disconected.
Tek-Tips is the largest IT community on the Internet today!
Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!
-
Congratulations cowski on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!
Pump Voltage
- Thread starter LavenburgElectric
- Start date
- Status
Hi
Check the head H and flow Q (pump nameplate) and type of pumped fluid, you will get the power at shaft using P=density x 9.81 x Q x H / efficiency.
Assume 70-75 % efficiency not irrealistic, except if wastewater submersible pump could be far lower sometimes (40-50%?).
Then the motor should be sized according to such power plus margin (+8 to +10%?)
Once you get the rated power of the motor, you need to account for motor efficiency (96%) and then you should come up with some figure about the electrical power.
With such power you should fall in some normalized range :
110 volts to 690 volts are often classified as low voltage units let say from 0.2 kW up to at least 750 kW.
Medium voltage at 3 kV (50 Hz) or up to 10 kV typically designed for use with motors rated to 375 kW and above.
this is just to tentatively help you have some guess...
Rgdrs
Wimple
Check the head H and flow Q (pump nameplate) and type of pumped fluid, you will get the power at shaft using P=density x 9.81 x Q x H / efficiency.
Assume 70-75 % efficiency not irrealistic, except if wastewater submersible pump could be far lower sometimes (40-50%?).
Then the motor should be sized according to such power plus margin (+8 to +10%?)
Once you get the rated power of the motor, you need to account for motor efficiency (96%) and then you should come up with some figure about the electrical power.
With such power you should fall in some normalized range :
110 volts to 690 volts are often classified as low voltage units let say from 0.2 kW up to at least 750 kW.
Medium voltage at 3 kV (50 Hz) or up to 10 kV typically designed for use with motors rated to 375 kW and above.
this is just to tentatively help you have some guess...
Rgdrs
Wimple
![[smile]](/data/assets/smilies/smile.gif "[smile] [smile]")
- Moderator
- #5
The first step is to examine the conductors to see if the wiring is suitable for low voltage (below 1000 V) or medium voltage. Then survey the voltages available in the area.
Determine the possible voltages and try with the lowest voltage first. Keep your tests short and monitor the current and discharge.
Hope that the pump is three phase. If it is an expensive pump, pull the pump.
It's a guess but there this may make it an educated guess.
Assume a starting current of 600% to 800%. At the correct voltage the running current should drop to or, more likely, below 1/6th to 1/8th of the starting current.
Also the running current may be below 80% of the ampacity of the motor conductors. Again an educated guess.
Bill
--------------------
"Why not the best?"
Jimmy Carter
Determine the possible voltages and try with the lowest voltage first. Keep your tests short and monitor the current and discharge.
Hope that the pump is three phase. If it is an expensive pump, pull the pump.
It's a guess but there this may make it an educated guess.
Assume a starting current of 600% to 800%. At the correct voltage the running current should drop to or, more likely, below 1/6th to 1/8th of the starting current.
Also the running current may be below 80% of the ampacity of the motor conductors. Again an educated guess.
Bill
--------------------
"Why not the best?"
Jimmy Carter
You say the power source has been disconnected - does that mean what it says - are the original power cables still there and near to the pump but terminated and not connected to the pump or have all electrics been removed from the general area OR has the pump been located somewhere else?
Your question is not reaaly clear.
Your question is not reaaly clear.
- Status
