Swapping Hydrovane motor

[tysonn]

Could anyone advise the procedure in swapping the motor from 3 phase to single phase on a Hydrovane?If the compressor currently has a 3hp motor and I intend to replace it with the same rating?Is it as straightforward as it sounds?

 

[tigler]

If it's the same or similar to the 501 model it's as simple as unbolting the motor, pulling it free from the coupling and bolting up the new motor.

 

[tysonn]

Its on Ebay at the moment 320829541012

 

[tigler]

Thats more or less the same, so the procedure I mentioned above applies. Easy peasy !
You just get a motor with the correct mounting flange, shaft size and foot and it's job done.
The pressure switch will have 3 contacts for 3 phase but just 2 would be used for single.

 

[tysonn]

Many thanks!Just hope I can afford it!

 

[brightspark]

Thats more or less the same, so the procedure I mentioned above applies. Easy peasy !
You just get a motor with the correct mounting flange, shaft size and foot and it's job done.
The pressure switch will have 3 contacts for 3 phase but just 2 would be used for single.

the thing to check is the contact rating in the pressure switch. the rating needs to be higher for single phase than it does for 3 phase it will give the amperage on a data plate

 

[madkayaker]

I have the same unit. There good compresses but the output volume is not that high so unless you have a motor already by the time you have a motor (it's a flange mount so many of the cheep ones might not fit) you could have got a decent size single phase unit.

 

[awemawson]

the thing to check is the contact rating in the pressure switch. the rating needs to be higher for single phase than it does for 3 phase it will give the amperage on a data plate

You can wire the three poles of the three phase contactor is parallel to bring the current rating up to what you need for single phase.

 

[dannyp]

sadly that dosent work, tryed it before one conatct allways makes slightly before the others so it ends up getting flashed hard every time.

just buy a contactor rated at more than the motors start current and use the pressure switch to turn the contactor one and off, the addde bonus is when it dose wear out it's not that epensive to change

 

[brightspark]

sadly that dosent work, tryed it before one conatct allways makes slightly before the others so it ends up getting flashed hard every time.

just buy a contactor rated at more than the motors start current and use the pressure switch to turn the contactor one and off, the addde bonus is when it dose wear out it's not that epensive to change

that is the corect way to do it but linking the 3 contacts together and using it as a single pole will last a long time if none of the contacts are pitted

 

[ford34/2]

not something I`m megga qualified in --but, If the compressor currently has a 3hp motor 3 Phase, I understand a similar 3Hp single phase, aint gonna have the same power, + it may have starting windings- can they cope?

Just a thought,

certainly on woodwork machinery, a 3 phase motor of given horepower is vastly superior to a similarly rated single pahase motor.

Stan

 

[tigler]

It won't be a problem, this model was supplied in single and 3 phase versions.
Also, a 3hp single phase must be the same power as a 3hp 3 phase but may have a little less starting torque.

 

[brightspark]

It won't be a problem, this model was supplied in single and 3 phase versions.
Also, a 3hp single phase must be the same power as a 3hp 3 phase but may have a little less starting torque.

yes spread over 3 phases. each contact will only be pulling about 5 amp flc whereas a single phase will be pulling about 12 amps and the starting torque will be more eficient than a sigle phase motor edit i thought we were taking about current draw on the pressure switch not motor eficiency another thing wether its single or 3 phase 3hp is 3hp whichever

 

[ford34/2]

copied and pasted from an electrical site

Installing a 1-phase motor in place of a 3-phase

Should you decide to change a 3-phase motor for a 1-phase one some thought is necessary to get the best out of the conversion. It is as well to bear in mind that a single-phase motor is not the direct equivalent of a three-phase type. A 1-phase motor is best run continuously near its rated capacity (i.e. worked nearly flat out); if the motor is switched on and off frequently against “no load” the windings will be damaged and, if run through a cycle where it is started, worked briefly, stopped and started again, the capacitor will fail.

A machine tool with a 1 h.p. 3-phase motor should, in theory, run just as well with a 1 h.p. 1-phase motor - but, life's not like that. If you need your machine to perform as well as it did with its original motor - and run to the same top speed without struggling (and it is by no means certain that you will) - you may find that, for power for power, for ease of starting and long-term reliability, a successful and reliable conversion to 1-phase requires a motor which is marked as being some 30% to 50% more powerful

When changing the motor(s) leave the original 3-phase wiring and switchgear as intact as possible and store the old motor safely inside the machine’s stand – i.e. where you can misplace it. Do not waste time trying to modify any of the original electrics; it is much simpler, and a lot safer, to fit new wiring, a new switch and a "no-volt" safety cut-out. Should the machine ever be put back on 3-phase, or wired with an inverter to give a variable-speed drive all you (or the next owner) needs to do replace the original motor - and hook up the wiring.

 

[awemawson]

Unless you have the replacement motor already it might be almost as cheap to buy an inverter single to three phase convertor off ebay, all you have to do then is wire the motor for delta (235v) rather than star (415v)

 

[tysonn]

Good idea to leave it unmessed with but the 3hp inverters on Ebay are £260 inc carriage.There are motors on there for half that(couldnt find any for £95 as someone had suggested were available in another thread?).