VSD on Hydr Power Pack

Possibly but that depends on the size of the system and what it does.

In a more practical sense if you cant afford the electricity you presently use you definitely cant afford the VFD and related control systems either.

Yes and No!

The cost of a VSD and a new motor and harmonic mitigation units (HMU) will not give you a ROI for many years.

Using your existing motor, with no HMU, might give you some savings now but you will quickly damage the motor as if its an older type, its not designed to take the stresses of operating under a VSD. The harmonics generated by the VSD, will cost you more overall in power usage throughout your operation.

However your proposal will work, that is, the pressure sensor will control a VSD and in theory save money, but not that much.

How are you cooling the oil at present? Large cooling unit with a fan, or A/C units?

Most of our power packs have not cooling at all. The oil temperature goes up to about 60 degree C and stays at that temperature until the machine is switched off. Should I look into cooling the oil? What method is best?

60°C is plenty moderate for oil temperature; do not worry about cooling it.

Radiator, with a small single phase fan forcing air through, if you think that the oil is getting too hot!!

Entirely possible but you should look into off loading the pump in other ways before you go to the expense of VSD. Why not a small accumulator? There are lots of options and you would need to explain what you are doing to narrow down the choices.

Oliver Dunthorne

Is an accumulator the same as a receiver in the pneumatics circuit?

My idea is to save electricity. The motor on hydraulic power packs run constantly while the machine only needs oil pressure from time to time. I noticed now that VSD is over the top but are they any simpler methods which would help saving energy?

Thanks, Jurgen

Simple method...Have you thought of a switch/motor control unit/DOL starter that will turn the motor/pump on & off as and when pressure is required? Could be automatic or manual!

However, if the pump is not working at 100%, that is suppling working pressure rather than maintaining system pressure, then there is the possibility that the motor may be running at idle amps or just above. (could be another topic)

There is only ONE real way of saving money, and that is to switch off lights, motors, A/C's etc, that are not being used at the time

Yes, an accumulator is exactly as you describe, same animal, different medium!

You already have some quality replies. "Yes" it's very possible, VFDs are set up this way everyday in that they take a signal from a temperature sensor and sent that signal to the VFD (VSD). The entire problem with your question is that this isn't a big energy saver. Depending on your particular situation it will probably increase your total costs.

If you provided some more information about run times, your set up parameters etc. you have a lot of people here that can give you some quality ideas.

Good luck.

Be careful if trying to use a VFD here. In many cases, the torque does not decrease with lower speed, and thus you may need a constant torque motor and VFD, both of which are more expensive than the more usual variable torque versions.