Inverter Tripping Main Panel

Looks like an ELCB..what make is it? Even with zoom, i couldn't make it out...

If it is an ELCB, then it will trip if there is a leakge current to earth. Please chack whether (a) there is any mention of trip threshold like 30mA and (b) whether there is a "Test trip" button..

Looks like an Earth Leakage Circuit Breaker. Tripping this breaker means that breaker is sensing leakages current in its earth wire. If you have magger, test the insulation of connected load.

He should try a "Megger".....

When you use only 2 phases of a 3 phase supply you get single phase. IE 400 v 3 phase then using only 2 of the phases you get 400 v single phase, or if you used as I think he may of been refering to, single phase 230 v to 3 phase 230 v. Either way IT IS STILL SINGLE PHASE I challenge you to draw the sine wave of a 2 phase supply to the connected load and please explain!

Cheers

Joe

GA for a good answer and a good question!!!

Gopal, you are not talking sense, of course you can........you just need the right electronics, called a "VFD" if I remember correctly. Its done all over the world!!!

It is a ELCB and i think it is 30mA range. Your circuit is direct connected to this ELCB or through a MCB?...please check it. If you are using the phase from the out of the ELCB and the neutral from the Input side, then ELCb will trip.

It is connected through a 40A MCB which is after this breaker. I'm assuming now from the comments that it is an ELCB. It does have a test button. I am not near it now to get the make. There are 2 No. neutral bars on the board, top left above the "ELCB" and top right and the suppply to the inverter is connected on to the top right just off the picture. The live is connected via the 40A breaker on the bottom right of the picture 3rd from the right.. If this is on the wrong neutral bar would it trip the "ELCB"? Thanks for all the help.

Please check the neutral of your invertor is connected from the neutral from the ELCB. your wiring should be ie both phase and neutral should be from the ELCB or both not through the ELCB. Any of this connected to seperate, that is the reason for tripping. It is not necessary that required earth leakage to trip in this condition.

Absolutely true!!!

Yes......my electrician did the same mistake a couple of years ago, it did not work and tripped immediately. He did say that it might not work, but that he could "do it properly" if it didn't......it didn't!!

If you make a drawing it is quite simple to see why......the load current is returning via another neutral path......even though at some point they become the same neutral later. My electrician had to rewire properly, since then, no problems.....

You have a point there, if the complete load is not connected on to the load side of the ELCB or RCD it will trip. Both Phase and Neutral must be connected to the load side of the circuit breaker, also as I am not familar with this breaker it may only be a earth leakage monitoring device and not an over current device, it may pay to ensure complete protection to also instal a standard circuit breaker on the load side of the ELCB.

Cheers

Joe

PLease quote rating of breaker & rating of lift motor.

It is connected through a 40A MCB which is after this breaker. I'm assuming now from the comments that it is an ELCB. It does have a test button. I am not near it now to get the make. There are 2 No. neutral bars on the board, top left above the "ELCB" and top right and the suppply to the inverter is connected on to the top right just off the picture. The live is connected via the 40A breaker on the bottom right of the picture 3rd from the right.. If this is on the wrong neutral bar would it trip the "ELCB"? Thanks for all the help.

Your board will have been wired something like this...

The loose ends after the individual MCBs go to the loads, and the other ends of the loads go to the netral bar.

Now, since the ELCB is a 4-pole one, all phase currents and any current returning through the neutral will go through the summation CT in the ELCB...as long as there is no leakage to earth, it will not trip, since the vector sum of the four currents is always zero. It will only trip if there is a leakage to earth, most likely cause being insulation failure somewhere...

Kvsridhar, Thank you for your help and your time. Some investigating to be done if there is a leak to earth. New cable only installed from the 40A MCB to the new inverter panel. So dont see where it could be there. Inside the new panel the power is connected through an isolator where the live and neutral and switched. After this the live, neutral and earth go straight to the top of the inverter. There is then the UVW "3phase 230V" supply to the 3 phase motor. I do not have an earth coming back from the motor.

Let me get this straight. You have only one motor on this? No other loads? Only UVW coming ? No neutral (not required if the motor is the only load)?

Yes. Only one motor. The motor is 3 phase it is running a hydraulic car lift. Reason for the inverter is to run the 3 phase motor with single phase power. I do also have to power a 24v transformer in the lift itself to release a solinoid for the lift to come down but this is wired separte to the inverter.

Ahhh..stupid of me not to have asked this before...no fault of yours, you did say in your original post that it was to power a car-lift motor.

Ok, this means that there is no neutral going from your inverter output to the motor, none needed. So, why don't you remove the neutral connection to the ELCB itself, both ends ? BUT BE CAREFUL. This is a safety issue. If there is ANY other load on the ELCB, you CANNOT remove the neutral.

If an ELCB is connected to a single phase load, then the neutral must pass through it so as to provide the balance current for the device to operate correctly, otherwise the unit will trip when the phase current exceeds the imbalance trip current setting. The solution is to reconnect the downstream neutral conductor to the ELCB, and not directly to the dis box neutral bar.

A neutral conductor is always required for a single phase load.

If there is no neutral downstream of the single-phase-to-three-phase equipment that operates the car lift motor that is driven off this circuit, then it is of no real consequence.

GA for a good, accurate and simple explanation!!

¿The ELCB in this example is connected to a 3-phase load, isn't it?

Regardless of single- or three-phase, if the downstream neutral is connected properly then the problem will be a connection from either a phase conductor vial a load, or the neutral conductor directly, to the earth conductor. An Electrician's installation checking equipment and procedure will reveal this to be the case.

Locating and correcting the fault is going to take a bit longer.

If it is wired correctly, then it is the RF Filters causing the problem. Refer to my first posting. RCD and ELCB's are for appilances that are plugged in, not for permanent installations.

Cheers

Joe

Many single phase to 3 phase inverters have input mains filtering to help stop the high frequency noise generated by the inverter from getting back into the AC line.

It could be that the internal input filter in the inverter is triggering the ELCB.

The inverter will most-likely have its own earth fault protection for the motor side so the ELCB is not necessary for safe motor operation.

I agree with this comment. Some inverters can have a 3rd harmonic component that is 25% greater than the fundamtal & this 3rd H current can trip an ELCB. So if the circuit wiring is correct I would consider looking at the harmonic components of the system.

Why bother, just make the car lift to be a permanently wired system and then you can by pass the ELCB or RCD.

Many low cost single phase (and three phase) inverters include an integrated EMC filter. The single phase filter design has an earth to line connected X capacitor that presents 'standing' (permamnent) earth leakage. It's common enough for this to trip the ELCB alone but it may be that it adds to other existing leakage to exceed the 30mA threshold.

If you can disconnect the filter to earth connection (some designs allow this by a switch or jumper) then your problem will likely go away. Many designs don't allow this though. If your supplier has supplied an integrated RF solution for elcb maybe you can return this and exchange for non filtered with a separate low earth leakage design filter (normally <1.5mA). Motor leakage currents will also add a little so reduce the switching (carrier) frequency of the inverter PWM output, say to 2kHz, this will help too and you can try straight away.

BTW, the earth fault protection of the VFD is aimed at protecting equipment from permanent damage and is not connected to the personnel protection targetted by ELCB at 30mA level. Normally, this should be permanently connected, in UK a pluggable earth should normally not exceed 3.5mA so requiring a low earth leakage design.

What brand VFD?
Does it have EMC filter integrated?

If so, what is the earth leakage?

Can it be disconnected / replaced?

Hope this helps..

Appalling rubbish and totally wrong!!!!!

Do not guess at things you have no idea about.......you just look (and are) a dangerous fool!!!

You also:-

Appalling rubbish and totally wrong!!!!!

Do not guess at things you have no idea about.......you just look (and are) a dangerous fool!!!

I really don't know much about this, but when we had a similar problem powering a large parts washer, we ended up building our own phase converter out of an idler motor the same size as the load motor (3hp in our case). A couple of capacitors were used to synchronize it all. My understanding is the inverters only simulate the third leg for start up, while an idler motor will produce the third leg continually so you are actually running three phase. I was told the inverters shut down the third leg after start up so you really are running on two which under powers the motor causing it to burn out. I could find and send the plans if you are interested, or just google .

It might be amusing to know what the ratings of the car lift motor are, such as voltage and FLA. If a 1-phase supply is feeding this, its current must be at least √3 * motor FLA (full load amps).

The hydraulic system is also relevant. Ideally, the motor should start without hydraulic resistance (i.e., on an open-center valve). Once the motor is up to speed, then operate the lifting valve.

From what I have seen thus far, I can't tell if either of these criteria has been satisfied.

I would also recommend some Panduit or like wireways in the control panel, which looks like stringy chicken guts.

Don't megger the circuit, if you megger it you may dammage the VS Drive.

The problem that you have is that the RF Filters are causing the Earth Leakage Circuit Breaker To Trip.

My suggestion is to wire in the car lift as a permanent installation, and do then you should be able to do away ELCB (Ie wire it to a circuit that is not monitored by the ELCB). When the car lift is wired permannently you do not require a ELCB or RCD Device to protect the installation.

The other option is depending on the VSD that you are using you can disconnect the RF Filters and the problem will go away, we have experienced this problem with mobile pumps in Wine processing plants, so the drives we use have the option of disconnecting the RF Filters.

I hope this is of help

Best Regards

Joe

Hi 21j,

My thoughts on this are that you should be using a phase converter, not a vsd and getting true 3 phase 440v from your single phase.

I run a 7.5 hp 440v motor from 240v single phase through a 15A trip and have no problems.

You now have many opinions from experts with actual experience. The consensus seems to be that ELCB (a)need not be and (b) must not be there. i agree. In fact after i said that you should disconnect the neutral, i was about say bypass the whole ELCB, since the motor is a dedicated load and doesn't need this. Well, i am glad that two people thought it was a good idea, and then one vored it is not, no issue.Much better answers are there now...

On the debate raging about conversion, i found this nice scheme... Miller something... any good?

Half-expected the image to be incomprehensible, but not this bad

Here is the link : http://www.electro-tech-online.com/attachments/re-projects/35774d1259363132-3-phase-converter-schematic-miller-system-3ph-converter.png

Ok. The ELCB is now by-passed. And there is no longer the tripping issue.

As with life there is another issue. The inverter builds up speed to the motor but the motors turns slow and heats up. Once or twice it has run correctly and raised the lift at a reasonable speed. But the majority of the time the motor just spins slowly and heats up. The motor has been changed to delta. There is a parameter in the inverter for the voltage, I am not sure whether this should be set to 230v or 380v. I know the inverter is giving 230v 3 phase.

The inverter is an Invertek Optidrive E2 4.0kW. The Motor it is driving is a 2.6kW 3 phase motor.

Sounds like the motor is stalling, so it's either overloaded or over / undervolted.

If the motor is in the 230V connection, you should set the inverter output to the same voltage and frequency. What is your motor rating data and your power supply? Where are you based?

BTW, Invertek E2 is only 2.2kW on single phase, did you use a 3 phase 220v unit now connected only on single phase? If there is an integrated filter this would cause very high earth leakage due to unbalanced connection.

To Simplify once and for all:

Frequency Inverters(VFD= Variable Frequency Drive = same):

-- You can have VFD that works on Single phase input and gives 3 phase output. ALSO you have those that require 3 phase input and give 3 phase output.

-- Voltage: If the input is single phase, 230V, the output can only be a maximum of 230V 3 phase. In general, the maximum input voltage is the maximum output voltage for these devices.

-- Connectio: If single phase and requires phase & Neutral, both these should come from the same ELCB (here you seem to have RCD = residual current differential circuit breaker.) output. BUT ADVISE to BY-PASS THE ELCB or RCD and connect directly from the C.B. before the RCD and use a Neutral before the RCD. { as mentioned by others, the VFD drice will create harmonics that will trip the RCD. You need special RCD that are specific for these...}

-- Motor goes slow: The Motor power must be checked and the settings of the Inverter parameters must match: If you have a start Delta motor (i.e. you can configure it Star or Delta), Check the voltages on the nameplate for each configuration. If in Delta it can take 380V and you give it 230V, then you will get less output power from it and it will struggle---> higher current since it will not reach it's normal speed---> it can stall and burnout!

If in Star it takes 230V, with your inverter, it will work but the output power will be limited to the Star configuration (Check nameplate to see if the amps rating in Star will give the same Output power... usually yes). The Torque will be less than in Delta configuration... which might be a problem in your lift usage.

Finally, if you need to run in delta (380V) then change the VFD to one that will get 3 phase 400V input and gives you the 400V (or 380) you might require for the motor.

It should be 230v