Thread: HY02D223B GND triggers RCD Problem

Originally Posted by atntias

Hello,
I have a 2.2kw chineese HY02D223B and have a little problem:
the device works only if the GND of the 220V is NOT connected and even runs the spindle fine.
as soon as I connect the GND, regardless if the spindle is connected or not - the power falls (residual-current device (RCD) triggers) i've tried it in diffrent location with same results. im connecting the 220v in the RST(tired all combinations RT,RS, ect..) connection and the gnd in the last one marked with the GND sign.

is it a defecitve device or is there some advice?

thanks

Hard to say, the RCD trips because there is an imbalance between the current in active and neutral, the load side of a vfd doesn't generally come into the equation since it's on the other side of the DC supply, (but you still need a protective ground on the motor) and shielding for EMI anyway..

Two possibilities come to mind.

1. There might be a fault in the VFD. Get an electrician to test it for you.

2. Might be an overly sensitive RCD.

When you switch the VFD on there will be a surge while the capacitors in the high voltage DC supply are charging, so there will be an imbalance for that short time, maybe that's enough to trip the RCD, Ask your friendly electrician to see if he can install an RCD that's suited to capacitive loads.

Regards
Ray

Not familiar with that model, but there may be some filtering at the input to stop noise from the VFD going back into the mains - that could include a cap to ground perhaps? A photo or two of the inverter's guts, particularly around the mains input might provides some clues.

That said, I had RCD problems with a large-ish Danfoss drive in that it'd trip the RCD when turning its 3-phase isolator off (but not when turning it on). Easiest solution in that case was to hard-wire it, hence no requirement for an RCD.

Originally Posted by RayG

When you switch the VFD on there will be a surge while the capacitors in the high voltage DC supply are charging, so there will be an imbalance for that short time

While there will be a surge whilst charging the caps, current should be sourced through the active, pass through the rectifier bank, charge the caps, and return through the opposite leg of the recifier and neutral. Therefore the active and neutral currents should remain balanced and not trip the RCD.

There is a possibility of the unit have a noise filter at the input, and this could have a capacitor connecting active to earth, but these are normally sized to provide a low impedence to high frequency noise components and a high impedance to mains frequencies. Hence current imbalance should be below the threshold limit for the RCD. Similar filters in early generation PC power supplies tended to trip some RCD's when they were first introduced, but the power supply designers fixed the problem by changing the filters in subsequent power supplies.

I would be on the lookout for things like VSD mounting screws contacting internal components and similar issues, and check other equipment powered through the RCD in case there is an existing imbalance current just below the RCD threshold, and the filter imbalance is sufficient to cause a trip. There are simple testers that can be purchased online or in stores like Bunnings, plug into a power point, indicate correct wiring of power points, extension cords etc that they are are connected to and in addition provide RCD trip current testing in 5mA steps. If one of these devices was used to test the RCD, and it was found to trip considerably below the nominal imbalance current that the RCD can tolerate, then it is a good indication that other devices powered through the RCD are having an effect on the unit, or that the RCD is tripping prematurely.

Just to be sure, you are talking about the ground on the right hand end of the terminal block?*
My VSD's have a ground symbol in the plastic at both ends of the terminal block. One on them certainly isnt ground.

Stuart

*I think for that model. they do move the ground around to three different places on different models.

Originally Posted by malb

While there will be a surge whilst charging the caps, current should be sourced through the active, pass through the rectifier bank, charge the caps, and return through the opposite leg of the recifier and neutral. Therefore the active and neutral currents should remain balanced and not trip the RCD.

There is a possibility of the unit have a noise filter at the input, and this could have a capacitor connecting active to earth, but these are normally sized to provide a low impedence to high frequency noise components and a high impedance to mains frequencies. Hence current imbalance should be below the threshold limit for the RCD. Similar filters in early generation PC power supplies tended to trip some RCD's when they were first introduced, but the power supply designers fixed the problem by changing the filters in subsequent power supplies.

I would be on the lookout for things like VSD mounting screws contacting internal components and similar issues, and check other equipment powered through the RCD in case there is an existing imbalance current just below the RCD threshold, and the filter imbalance is sufficient to cause a trip. There are simple testers that can be purchased online or in stores like Bunnings, plug into a power point, indicate correct wiring of power points, extension cords etc that they are are connected to and in addition provide RCD trip current testing in 5mA steps. If one of these devices was used to test the RCD, and it was found to trip considerably below the nominal imbalance current that the RCD can tolerate, then it is a good indication that other devices powered through the RCD are having an effect on the unit, or that the RCD is tripping prematurely.

Yes all good points, the type of RCD i'm referring to is the "B" type, that I think might be more suitable.. ( assuming of course that there is no real fault!! )

From ABB's web site...ABB Classification of RCDs upon detectable wave form - Residual Current Devices RCDs (Modular DIN Rail Products)

▪ AC type, for alternating current only
▪ A type, for alternating and/or pulsating current with DC components
▪ B type, for alternating and/or pulsating current with DC components and continuous fault current.

AC type RCDs are suitable for all systems where users have sinusoidal earth current. They are not sensitive to impulsive leakage currents up to a peak of 250 A (8/20 wave form) such as those which may occur due to overlapping voltage impulses on the mains (e.g.: insertion of fluorescent bulbs, X-ray equipment, data processing systems and SCR controls).

A type RCDs are not sensitive to impulsive currents up to a peak of 250 A (8/20 wave form). They are particularly suitable for protecting systems in which the user equipment has electronic devices for rectifying the current or phase cutting adjustment of a physical quantity (speed temperature, light intensity etc.) supplied directly by the mains without the insertion of transformers and insulated in class I (class II is, by definition, free of faults to earth).These devices may generate a pulsating fault current with DC components which the A type RCD can recognize.

B type RCDs are recommended for use with drives and inverters for supplying motors for pumps, lifts, textile machines, machine tools etc., since they recognize a continuous fault current with a low level ripple.

Regards
Ray

I'm sorry, but from your initial query I could not make out exactly how you are connecting up the VFD.
You are only connecting two wires to two of the power inputs R,S and T aren't you? and then connecting the earth wire to the connection on the right hand end?

Originally Posted by Bob Willson

I'm sorry, but from your initial query I could not make out exactly how you are connecting up the VFD.
You are only connecting two wires to two of the power inputs R,S and T aren't you? and then connecting the earth wire to the connection on the right hand end?

indeed.

after i gave it to my electrician friend, he opens it up and found that a wire was short circuiting one of the transistors.
as soon as that was removed everything was working fine!!!
thanks to every one for the help!

-atntias

Well it is good to know that your protection system was working properly and advising you of a potentially fatal flaw.

I think that with most of this Chinese stuff, the first thing we should do is disassemble the things and then put them back together again. Twice now, I have found a VFD with a wire that wasn't connected properly.

Maybe the Chinese just don't like us and are trying to kill us off surreptitiously.

Glad you got it fixed