Running a DOL starter from a VFD

[Greymoonstar]

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)

 

[System Protection]

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?

 

[mparenteau]

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

 

[LittleInch]

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?

 

[Greymoonstar]

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)

 

[LittleInch]

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.

 

[waross]

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.

 

[edison123]

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.

 

[jraef]

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.