Continuous use of a phase convertor.

[Nathan SharpeParticipant @nathansharpe19746]

Can a phase converter, not a VFD/Inverter, be run continuously ? It would be powered and in ready mode most of the time and in use (on demand by the load) two to four times a day. Please do not tell me about VFD's/ Inverter's . They are not suited to the possible application and we have already tried them. We do not have 3ph supply available, do have dual voltage motors and have reconfigured to 220/230 v 3ph . My workshop is run from a Transwave converter and has been for 20 years without any hassle but it is a home/hobby workshop and not an everyday continuous use application. I need to know if I can run a 24 hour/7 day/52 week system on a converter. Can any of you help? Nathan.

[Nathan SharpeParticipant @nathansharpe19746]

[vintagengineerParticipant @vintagengineer]

You could ask Transwave. I have one of their converters with a built in motor and fan and I run it for several hours at a time.

[Nathan SharpeParticipant @nathansharpe19746]

Thanks vintagengineer, but what I'm looking for is a knowledge from a source which is non manufacturer but IS from someone who has knowledge of this through work or self use. I have had enough of the "advice" from sales orientated tech departments. I need advice from real working humans. Nathan.

[John ReeseParticipant @johnreese12848]

I run my 3 phase tools on a rotary phase converter. I turn it on when I enter the shop, off when I leave. My mill is 3 hp., lathe 2 hp., drill 1 hp., Surface grinder and small lathe 1/2 hp. I turn them on and off as needed with the phase converter running continuously.

[martin perman 1Participant @martinperman1]

At work we have single to three phase converters running 2hp submersible water pumps 24/7, 365 days a year with no problems, any issues are usually caused by a cooling fan failing allowing the unit to over heat otherwise no problems.

Martin P

[ScrumpyParticipant @scrumpy]

I have two transwave converters in my workshop , A friend who has a fishery was so impressed with them he purchased one and runs a pump and a vacuum pump 24 hrs a day with no problems

[Nathan SharpeParticipant @nathansharpe19746]

Thank you Martin P and Scrumpy. That is the exact application I have in mind . We need to power a 3ph pump control panel running 2 sub pumps from a single phase supply . We currently have two single phase in three phase out (230v) inverters trying to do the job and they do work after a fashion but are unreliable so far. It looks like they do not like too many switching operations instigated by the float switches and they also add a level of complexity that I do not like on what should be a simple system ! Nathan.

[JonParticipant @jon]

Nathan you could try a respectable branded inverter such as Mitsubishi.
Seen some cheap inverters stating not for continuous use.
My inverter will run all day long and made for it, power whole shop from one unit as would be plugged in to a 3ph supply or rotary convertor ie through control panels. I wouldn't like to run my Transwave rotary for very long kept as backup for when the 1ph 240v to 3ph 400v inverter goes down.

[Mark RandParticipant @markrand96270]

My Danfoss VLT 500 series inverter supplies three phase to all the 3ph machines in the shop. No separate controls, just plug the machines into the wall sockets and run them. Currently one lathe, one mill and one surface grinder, with nine motors between them. It just works and powers any or all of them together (With the limitation that I can only run two machines at a time, unless the lad is there to run the third).

Remember, inverters are made from a few Watts up to hundreds of MW, you just have to get one with a suitable specification.

[duncan webster 1Participant @duncanwebster1]

Phase converter is a box of capacitors and inductors, so I don't see any reason it can't be continuously energised, but I also can't see why vfd isn't reliable. You've not got the switch between motor and VFD have you? This is a well known way of destroying them, you have to use the start/stop inputs to the box of tricks.

[Mark RandParticipant @markrand96270]

See my comment above. An inverter with no limitation on downstream switching does not have this issue.

[JonParticipant @jon]

I can confirm that Mark and Danfoss being a respectable brand for continuous use, one reason theyre dearer.

Apart from delivering 3ph 400v output just the way a rotary pseudo 3ph works, just plug machines in exactly the same way via plug and sockets.
Output of mine goes to several 3ph sockets around the shop hard wired in. Can run several machines all at once with no configuring or soft start. eg output where lathe plugged in goes to machines on/off isolator then via multiple contactors, switches, coolant and powering the low voltage transformer for other trips as in spindle start/stop/reverse, emergency stop, spindle cover trip taped open permanently etc exactly the way it was made around 1970.
They don't all need to go direct to motor then faff about with each machines trips and cabling back to the inverter.

Do know a few that run premises from exactly the same type of inverters with additional filters running an array of 3 to 5 axis cnc just plugged in, nothing new been around for some time but at a cost.

[MuzzerParticipant @muzzer]

Posted by Mark Rand on 26/03/2017 10:42:53:

See my comment above. An inverter with no limitation on downstream switching does not have this issue.

Indeed they would be – but they are far from commonplace. Care to share details of a real example for our reference?

Murray

[Mark RandParticipant @markrand96270]

Posted by Muzzer on 26/03/2017 19:35:36:

Indeed they would be – but they are far from commonplace. Care to share details of a real example for our reference?

Murray

The one I referenced in the first post:- a Danfoss VLT 5000 series. In this instance, it's a 23kVA one that I've down rated to feed from single phase.

There were three similar ones on EBay a few weeks ago.

[Nathan SharpeParticipant @nathansharpe19746]

Thank you all for your input. The inverters we are using ( Invertek Optidrive e3) are correctly configured and we are using our control circuit on the correct IP/OP terminals. They are British made and have a specific parameter set for pumps. My question was answered by both Martin P and Scrumpy after that I lost interest. I did ask that you did not tell me about inverters, I know about inverters, we install 35/40 inverter driven systems each year but they have not been reliable or effective on this job and I need to find another way to power these sewage pumps before the ground floor flats start to flood AGAIN! Nathan.

[Nathan SharpeParticipant @nathansharpe19746]

An edit to my previous post. We design and install inverter driven water pumping stations where I can give more info via pressure/flow/level sensors to the inverter to prepare it for a start and to allow it to monitor these parameters and therefore deal with them before a sensor driven stop. With sewage being pumped into a" public" sewer we are pumping into an open ended pipe so we do not have the gradual increase in pressure to work with, flowmeters cease to read even with Magflow units and ultrasonic level controls are thrown into disarray because of the very "splashy" flow into most private sewage wet wells. We rely on float switches, a coarse on/off action, which could happen and does happen to the upper float quite a few times before a positive on switching is achieved. We do loads of sewage work ( the majority of our work) but prefer a standard DOL/Star Delta system for both single and three phase stations. This particular job has no 3ph supply available but my boss has specified 3ph pumps to the client. Nathan.

[Mark RandParticipant @markrand96270]

On the switching problems. is it possible to use a 'debounce' circuit or software in the PLC (if used) to reduce the strain on the supply/contactors/motor by generating a single turn-on rather than rattling everything untill things settle down?

PS:- Sorry to have dragged your thread into talk of inverters, but I've used/worked with ones that expect to be abused like any other source of supply.

[MuzzerParticipant @muzzer]

Mark – yes, I can see they have their benefits, being rated for unconditional witching on the output. The 23kVA rating is commendably OTT, which I guess works nicely for multiple machines.

In my applications, I have tended to go for one VFD per machine, so that I have separate control of each individual machine (as in variable frequency), plus things like thermal / overload protection, low speed torque boost, slave operation etc. Obviously more expensive this way but depends if you value that additional versatility. I like to be able to control the speed of my machines from their pendants and in the case of the CNC mill, I need to be able to control its operation from the main controller.

Murray

[Nathan SharpeParticipant @nathansharpe19746]

Evening all. Mark, I wish we could go that way but the cost would be prohibitive! Like Muzzer ,I prefer one VFD/machine. I do normally have to share the control circuit via a "flip/flop" or switching relay and yes all circuits are debounced. The currently faulty inverter has been sent back to the manufacturer for testing and repair/full report. We will continue to support this manufacturer because of their support system. The system is working as designed but on one pump. We have asked another of our suppliers if they could supply a standard panel with phase conversion built in and their answer was "We do it all the time " , so a site visit has been arranged and I will await their design with bated breath ! They tell us that their solution fits within an existing panel (Theirs) alongside of the standard control gear, I will report back to you all if this is something which could be a legit solution for my problem and,I suspect, many problems suffered by others on here who need a non inverter 3ph supply. Nathan.

[Nathan SharpeParticipant @nathansharpe19746]

Evening all, I finally have the time to report on my end result. Our suppliers visited site, looked at what we had installed, laughed and went away. Now , nearly six weeks after their visit, a design arrived with their quote, for exactly what we had already installed! They even use the same inverters as us with external controls connected in the same way. We decided to decline their offer to build and install by the end of June and were horrified by the cost which was greater than 4 times our cost for a now working system. The inverters seem to have had component issues which are now solved , we were sent 2 FOC to fit and had our originals repaired, again FOC. Nathan.

[Nathan SharpeParticipant @nathansharpe19746]

This saga continues ! Both pumps are burnt out but both inverters are O/K. We had all six leads from the motors available to reconfigure ( no neutral point ) so phase to phase we still had 400v and phase to earth 230v . Has anyone come across a modern 3 ph motor that cannot be reconfigured between star and delta? Nathan.

[EmgeeParticipant @emgee]

Hi Nathan

If the pumps were configured correctly and the VFD units set to the correct parameters then surely the VFD's must be suspect ?

Emgee

[JonParticipant @jon]

Here you go Nathan not sure if this will help.

https://www.quora.com/How-do-I-connect-3-phase-motors-in-star-and-delta-connection

[Nathan SharpeParticipant @nathansharpe19746]

Emgee and Jon. Thank you for your continued interest!

I do suspect the VFD's. Motor re configs we do every day . The guy that did the work for us is the son of a late friend and colleague who I would trust with any motor/panel job , knowing that he was trained by his father I'll trust his son's work to the same extent . We're being told by the pump supplier that these motors cannot be run in Delta but not why. From the dark depths of the past I have a vague memory that the gauge of wire in the coils may be the limiting factor? My idiot employer allowed both pump and VFD suppliers to talk to each other so now we get the same story for the VFD's . Given that our panel guy is self employed,as am I, my inclination is to throw the problem back to our employer who overrode our concerns about the reliability of the system . The client was advised by the idiot employer that 3ph was the way to go, not us. We're now going to install a 1ph system at added cost.

Nathan.

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