Removing 3 phase power onboard

[GoneDiving]

I'm looking at removing 3 phase supply from my trawler by converting an engine room fan (easy) and an electric over hydraulic windlass to single phase.

For the windlass, I'm undecided between fitting a single phase motor with softstart or retaining the 3 phase motor but fitting a 230 to 380v VFD.

Costs for both options are about the same.

My large dive compressor at home has run for years using a 1 to 3 phase vfd but that's not in a marine environment. I have no experience with the reliability of soft starts.

Has anyone run either in a marine environment? Comments?

Thanks

 

[Ted]

I have 2 soft starts using 110 volt DC, they seem to work fine. Been on the boat long before I got it.

Ted

 

[Ski in NC]

I have two machines in my shop that run VFD to get 3ph 240 out of 1ph 240. Been very reliable. They are not in marine environment, but looking at their construction they should be fine on a boat, as long as they are put in a dry location.

On mine, the soft start feature only works if operated from the local control. If you start the motor by switching at output cable, it zings right up to whatever rpm it is set to. Also if input power is interrupted, you have to turn the thing on locally. That's just the way my units are, other types might be different.

 

[C lectric]

How is the 3 phase power produced and at what voltage as it is now?

 

[GoneDiving]

How is the 3 phase power produced and at what voltage as it is now?

3 phase is currently produced by a 30kva diesel generator.
AC voltages on board are 230vac single phase, 400vac three phase at 50hz. I'm in Australia so no US style split phase.

The only 3phase equipment is the 7.5kw elec/hyd windlass and 0.75kw ER fan.

Cheers

 

[GoneDiving]

I have 2 soft starts using 110 volt DC, they seem to work fine.

Ted

110vdc? Should this be vac?

Thanks

 

[GoneDiving]

I have two machines in my shop that run VFD to get 3ph 240 out of 1ph 240. Been very reliable. They are not in marine environment, but looking at their construction they should be fine on a boat, as long as they are put in a dry location.

On mine, the soft start feature only works if operated from the local control. If you start the motor by switching at output cable, it zings right up to whatever rpm it is set to. Also if input power is interrupted, you have to turn the thing on locally. That's just the way my units are, other types might be different.

Sounds similar to my dive compressor.

I use the ramp up to control inrush current. The vfd is double the rating of the motor to provide sufficient single phase current input capacity. I switch on the input side of the vfd as I was told switching the output can fry the unit. Not sure if that is true but it's worked for years.

If anything I see the hyd-power pack as easier to start as it has zero load until the windlass is engaged. Inrush current is my main concern on start up.

Thanks

 

[Ted]

110vdc? Should this be vac?

Thanks

Nope, DC as stated.

Ted

 

[C lectric]

***********I'm looking at removing 3 phase supply from my trawler by converting an engine room fan (easy) and an electric over hydraulic windlass to single phase.************
Does this mean you are replacing the generator with a single phase unit?

These are just my thoughts and I am no expert but why are you replacing , hopefully, good 3 phase motors with single phase motors?

VFD are a good way to go if all you have is single phase supply and need to run a 3 phase motor. But unless I am missing something big time I don't see any advantage particularly when the generator is 3 phase.

I see some disadvantages.

3 phase motors are better/stronger starting on 3 phase than the same HP in single phase, they draw less current per conductor , although same watts sort of within reason per HP, and are usually physically smaller than an equivalent HP single phase motor.

Reversing is usually simpler from outside the motor.


If you are replacing the generator with a single phase unit that is a different matter, but otherwise I see no advantage and some disadvantages.

 

[GoneDiving]

Does this mean you are replacing the generator with a single phase unit?

These are just my thoughts and I am no expert but why are you replacing , hopefully, good 3 phase motors with single phase motors?

The vessel currently has 3 generators and 4 voltages. The largest generator supplies 3 phase. It also runs 24/7 while underway as it is the only source of 24vdc. By standardizing to single phase and 12vdc I'll gain 15% fuel consumption, noise and vibration reduction (its louder than the mains), a large area in the ER, and several systems that don't need to be maintained.

Thanks.

 

[caltexflanc]

Personally I am biased to reduce complications and avoid introducing additional components (potential points of failure). So, me, I'd switch out the motor, especially since the difference in cost is apparently nominal.