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Running a DOL starter from a VFD 1

Greymoonstar

Marine/Ocean
Jan 30, 2025
5
I am trying to run a DOL starter for a Marine Hydraulic Power Unit.
The Starter runs a 220V 3-phase 60hz 2.2kW motor.
I am in the UK and my Factory supplies are 230VAC Single Phase and 415V 3-phase.
I have tried running a VFD as the supply to the starter, but when I engage to motor contactor in the starter, the VFD triggers a constant speed overcurrent error and cuts the supply.

The starter will not allow the motor contactor to engage without 3-phase, but if the vfd is running before I start the motor, it errors and cuts the supply.

Any ideas?

(First time poster)
 
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The output of the VFD should go direct to the motor.

Sounds like you have the contactor in between the motor and the VFD output?
 
There are usually interlocks between a VFD, load side disconnect and the VFD itself (I've never used a starter on the load side of a VFD, but have installed disconnects on the load side of a VFD for local isolation). Drives don't like switching actions on the load side of their terminals while a load is being driven, hence the VFD cutting out.

Mike
 
A couple of questions.

Why are you running a 60Htz machine of such small power in 50Htz land?

If this is a DOL starter, why not use a 50Htz machine?

Or if you really want to just use a 60 Htz machine buy a static convertor https://powersystemsinternational.c...c-frequency-converters/50-to-60hz-60-to-50hz/

Or just plug in your VFD to the machine direct and tell it to ramp up in 5 seconds or whatever the minimum is on the VFD control.

Sounds like you're trying to use a VFD controller to give you 60Htz, then plug in a DOL starter which is going to give you 4-6 X FLC as a starting current so not a surprise the VFD unit doesn't like it.

What's the details on the VFD unit?
 
The HPU and DOL starter are for a marine steering system for a vessel in South America. The onboard power will therefore be a 60hz 3phase from their generator direct to the starter. So the contactor will be the only control element for the motor.

But I need to test run the system for the classification society surveyor before it gets sent to the shipyard for installation. Hence the need for running a 220V 3ph 60hz supply into the starter, I have to prove all it's safeties and backup systems function correctly.

I have a converter for 415V 3ph, but it's min output is 380V and the vessel can't supply that (I believe it is a refit to an older vessel, so no upgrade to the power supply)
 
If you can get 380V 60 htz then all you need is a step down transformer?

At that power you sound be able to hire one?
OR hire a 220V 60 Htz generator.
Your VFD is just not set up to do a DOL start.
 
but it's min output is 380V
380 Volts is often derived from three 220 Volt windings connected in star.
If that is the case with your converter, investigate the possibility of temporarily reconnecting the windings in delta for 220 Volts.
 
As OEM, invest in a 220 V/ 60 Hz diesel generator or in a 415 V/220 V transformer and feed it via your 415 V VFD.
 
Bottom line, VFDs are not made to do this. They are transistor based devices, and the AC output is not truly AC, it is pseudo-AC, relying on the inductive time constant if the motor windings to help make it act like AC. But in the first instant that the motor windings are energized by the contactor when the VFD is not ramping from zero as it’s designed to do, that inductive circuit is not yet present. So the instantaneous magnetizing inrush current of those first DC pulses is far far higher than what the transistors can handle and the transistor manufacturers build in a protection circuit that looks at the rate of rise of the current to immediately clamp the firing circuits of the transistors, hopefully fast enough to prevent their destruction.

It is theoretically possible for a drive that is sufficiently large enough to handle some of the surge and then clamp the current fast enough to prevent damage, I recently came across one that did that, it went into current limit fast enough when it was connected to a motor that was half of its rating. But when they connected to a motor it was rated for and closed the contactor, it instantly tripped. So in theory you MIGHT be able to double the size of your drive and try it again, but there is no guarantee of it working.
 
20250131_081605.jpg20250121_140359.jpg

So these are the details of the VFD and HPU motor.

So from what you guys have said, the vfd is simply not man enough to handle the starting current.
So I need to source a more appropriate power supply.

In the meantime, if I disconnect the HPU from the starter, I should be able to test the phase detector, switching logic and alarm circuits from the vfd.

Then if I reconnect the hpu, force close the contactor and Then start the vfd, the vfd should run the motor and allow me to test the hpu in running condition.
 
Or… close the contactor BEFORE giving the VFD a Run command. Tie the Run command of the VFD to an aux. contact of the contactor.
 
You put the VFD where the FV starter is so the controls are always powered from the single phase input and then get rid of the phase detector since it is not needed with the VFD running the motor.
 
Thanks for all the suggestions. It has been really helpful.

As mentioned before the point is to test the operation of the DOL Starter and the HPU.

The VFD will not be present in the final installation (A South-American built yacht).

As this is for a marine steering system it has to pass both SOLAS and class requirements, hence the requirement for 3 phase detection (which enables automatic motor restarting and backup motor starting in case of phase failure) which cannot be bypassed as this is a required element of the test.
The use of the vfd was as a budget friendly attempt to provide a 220V 3phase 60hz for what may be a one-off system.

If we build anymore of these I will definitely source a more appropriate power-source.
 
View attachment 4223View attachment 4224

So these are the details of the VFD and HPU motor.

So from what you guys have said, the vfd is simply not man enough to handle the starting current.
So I need to source a more appropriate power supply.

In the meantime, if I disconnect the HPU from the starter, I should be able to test the phase detector, switching logic and alarm circuits from the vfd.

Then if I reconnect the hpu, force close the contactor and Then start the vfd, the vfd should run the motor and allow me to test the hpu in running condition.
That sounds like a possible way to at least test some of the components, yes.

Let us know if it works
 
If the motor will be started DOL in service, you should test it, DOL.
The VFD is not suitable for a DOL test for a number of reasons.

FORGET THE VFD AND DO THE TEST PROPERLY WITH A SOURCE CAPABLE OF STARTING THAT MOTOR DOL.
There are ways to start the motor with the VFD;
BUT
There is
no way to do a VALID DOL test with that VFD.
Bite the bullet and do it properly.
Consider the difference between
testing the motor versus starting the motor.
Alternatives:
Why not transformers? 50 Hz versus 60 Hz.
Rent a generator. Normally 3 times the KVA rating of the motor will start the motor;
But
The frequency dip and the voltage dip may be excessive.
For a valid test I suggest renting a gen-set of at least 6 times the KVA rating of the motor.

That should start the motor DOL without the possible complications of excess voltage dip, excess frequency dip and possible UFRO action.

The HPU and DOL starter are for a marine steering system for a vessel in South America. The onboard power will therefore be a 60hz 3phase from their generator direct to the starter. So the contactor will be the only control element for the motor.
Another option is to replace the phase rotation check relay with the VFD and ship the VFD as part of the HPU.
Without knowing the size of the auxiliaries on the ship, including the VFD as part of the HPU will allow the HPU to start reliably in the event that the auxiliary generator does not have enough spare capacity for a clean DOL start of the motor.
.
 
Your motor is 220V 60hz and your available power is 230V 60hz? I don't see any problems here. Plug it in and go. If you must have 220V, bucking transformers are available.
 
Your motor is 220V 60hz and your available power is 230V 60hz? I don't see any problems here. Plug it in and go. If you must have 220V, bucking transformers are available.
His 230V supply is single phase and 50hz.

He is trying to perform testing from the UK. After installation the source voltage will be the necessary 230V 3 phase 60hz.
 
And the problem is not so much starting the motor as it is doing a valid DOL test on a similar supply to what will be encountered in the field.
A valid DOL test will be a DOL test on on a firm supply.
The motor KVA is 3.1 KVA.
Rent a 20 KVA gen-set or larger and test away.
 
Do I see this correctly?
A single phase driving a VFD to 3 phase motor?

You have to have a VFD that is twice the size of the motor to do this, or it will trip.

Best to do it correctly like the previous post.
 

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