Accelation Time 1

[electricmotors]

We have a booster pump driven by a motor to boost a product in the pipeline to a shipper pump also driven by a motor. When we start the motor of the shipper pump it takes 3.3 second to accelarte increasing the pressure of the line more than the premissive limit on the line which also cause the presure drop at the booster side to zero (0)psi which cause the pump to trip. Now, is there a way to make the accelartion time of the motor longer than 3.3 second up to 15 second without affecting the motor.\

 

[teco]

electricmotors:-
it apears that you are starting the motor direct on line, hence the short acceleration time (also high accelerating torque and line current).
the options you have got are not limited, with modern day electronics you can ether use a variable frequency drive with an extended ramp time this reducers the start current and ajusts your accelerating torque to a controlled level (either speed or pressure)
or a soft start unit with an exstended ramp time. if you contact any electronic soft start or variable frequency drive manufacturer with this problem we are sure they will be able to assist.

 

[xnuke]

I recommend a soft start. Many are available with a variety of start and stop profiles, so you can select the profile that fits your need best. They also usually cost less than a variable frequency drive.

 

[don01]

as the guys above have said a vfd or softstart will give you ramping capability.
But have you looked at your piping and pumping installation. Your booster pump is over sized for your transport pump. The surge from the booster pump should not be of that order of magnitude. I will assume these are centrifical type pumps. If your transport pump is pd or gear you got real problems trying to shove more up its bum!! It must be very carefully sized ~ talk to the supplier

Consider the piping between the 2 pumps, you should have quite a large relative volume there. Also restrict the inlet to the booster pump BEFORE you start up ~ this is normal operating proceedure in my little world.
When the booster has run up then by hand open the valve monitoring the discharge pressure of the booster

If you go for an electronic solution then incorporate a pressure feed back from the booster discharge. This could be used to control the ramp rate.

Regards Don

 

[jbartos]

Suggestion: Reference:
1. IEEE Std 399-1997 IEEE Recommended Practice for Industrial and Commercial Power Systems Analysis
Perform an accelerating-time study in accordance with:
1. Par 9.3.2 Analyzing Starting Requirements
2. Par 9.4.3 The speed-torque and acceleration time analysis
3. Par 9.6.5 The speed-torque and motor-accelerating time analysis
This may lead to the simpler solutions than those outlined above since there are many squirrel-cage induction motors starting in your specified time interval, e.g. large fans. Incidentally, how had these applications been implemented before the ac motor drives started?