HiI have little problem figuring out problem with this drive. Resistance between earth and phases is about 7Moms, is it enough?Not for me, and not for some VFDs and it's mode dependent, not sure if its adjustable via parameters in a Danfoss drive. What was the voltage of the test? At 500v on a Fluke Megohmeter, I look for 100Mohm. I have seen old V/Hz vfds that will work down to about 2-3Mohms, and my big Toshiba's won't clear the fault if the reading is less than about 120Mohm!When problem, appears I just disconnect and connect buses inside FC300, and problem disappears for month or week. Seems to me that problem is with electronics. Any suggestion for further diagnostics?ThanksYou should be able to power cycle the drive without opening it by removing incoming power.
I suggest verifying the DC Bus during this bleed down time for safety and to note if it doesn't discharge at a nice smooth rate. I have found simple blown components in various VFD input circuits that were easier to repair in place on 50HP drives.But all drives I have worked with consider a ground fault to be the worst of the worst kind of fault, so they force a hard power down (wait up to five minutes) and reboot. During this time, you are expected to raise the leakage resistance to an acceptable level.Horsepower, type of conductor and rough length could be important factors as well as any local disconnects. Always disconnect the motor leads at the vfd and megger the entire circuit 'as seen' by the VFD while ensuring you don't zap the poor drive output with 500-1000V, then if the readings are bad, disconnect the wiring from the motor and test each separately. Cheap wire becomes perforated with conduction when noisy VFD spikes beat on it for years.
We have washdown, so local disconnects are the most frequent offenders of opne phases and ground faults, followed by breakdown of cheap wire, but by then we have often toasted the motor too.Paul. Not for me, and not for some VFDs and it's mode dependent, not sure if its adjustable via parameters in a Danfoss drive.
What was the voltage of the test? At 500v on a Fluke Megohmeter, I look for 100Mohm. I have seen old V/Hz vfds that will work down to about 2-3Mohms, and my big Toshiba's won't clear the fault if the reading is less than about 120Mohm!You should be able to power cycle the drive without opening it by removing incoming power. I suggest verifying the DC Bus during this bleed down time for safety and to note if it doesn't discharge at a nice smooth rate.
I have found simple blown components in various VFD input circuits that were easier to repair in place on 50HP drives.But all drives I have worked with consider a ground fault to be the worst of the worst kind of fault, so they force a hard power down (wait up to five minutes) and reboot. During this time, you are expected to raise the leakage resistance to an acceptable level.Horsepower, type of conductor and rough length could be important factors as well as any local disconnects. Always disconnect the motor leads at the vfd and megger the entire circuit 'as seen' by the VFD while ensuring you don't zap the poor drive output with 500-1000V, then if the readings are bad, disconnect the wiring from the motor and test each separately. Cheap wire becomes perforated with conduction when noisy VFD spikes beat on it for years.
We have washdown, so local disconnects are the most frequent offenders of opne phases and ground faults, followed by breakdown of cheap wire, but by then we have often toasted the motor too.PaulWhen I tested with old megaometer on 1000V 7Mohm and on 1500V result was 4Mohm.We make disconnections inside drive because we suspect that contacts could be oxidative, which results in resistance between contacts in control circuits. This however is only speculation, the fact is that this procedure helps. We tried disconnecting drive from power for 10 min and no luck.Thanks for advices. We always disconnect drives and other electronic devices before high voltage tests.We also tested cables separately result was infinity. As MikeW said, it depends on the drive. But up to 40 min is what the manual says!What is the size of the drive?In the larger sizes you are able to exchange the Current Transducers, and if these are not calibrated you will get an Alarm 14. Doing a AMA or even a reduced AMA can help with this.If the drive is old the CT's may also have drifted!Another cause might be the flatcables connecting the Control Card, Power Card and Relay Card, if one of these have a bad connection you can also see Alarm 14.Best regards,Michaldk.
HiI have little problem figuring out problem with this drive. Resistance between earth and phases is about 7Moms, is it enough?
When problem, appears I just disconnect and connect buses inside FC300, and problem disappears for month or week. Seems to me that problem is with electronics. Any suggestion for further diagnostics?ThanksWe have had some VLT5000 from Dan Foss, which will get a false Earth Fault trip, for Bad Power boards, or a bad ribbon cable between the Control board, and the power board. Also, if the drive has been in service for a while, and it is not an Inverter/Heavy duty motor, I've heard that because of the switching frequency, you can get an earth fault, that won't show up on a Megger. If you think this might be the case, you can try lowering the switching frequency. Are you certain you have no earth fault?I know you stated you tested and had 7Mohms.
I once had a situation where a drive was tripping intermittently and testing fine. I eventually traced to the glanding of the local isolator, a nick in a motor tail to the metal SWA gland, only showing due to machine vibration!Is the motor cabling passing through a damp area?Have you got a spare drive?.I have no spare drive. And my boss is kinda evading this problem and solution for now is reconnecting cables inside this drive.If my cables were 'leaking' earth current there should be persistent problem or some correlations must appear with machine vibration or humidity and earth fault, but this does not explain how problem disappears for few days when internal cables of drive are reconnected.
I cant simply ignore this fact and assume there is leakage somewhere I only can suspect faulty drive electronics.Thx for answers. Hi all,I had this a while ago on a VLT5000. The chap at Danfoss gave me some instructions to follow.Disconnect motor from inverter.Run the inverter and change display status to Amps.If it reads 0.01 amps its good, if it reads 0.5 amps or higher then upload your parameters.Hold the 'Display status, menu, change data and OK' keys simultaneously for 10 seconds.Cycle the power and then download your parameters again.This worked for me. Obviously if your not using a VLT5000 then your keys may be different, perhaps Danfoss can advise you of the correct keys on the 300 series unit. Hi Nightex,I will give this a try. I have 15 66kW VFD's and I seem to keep getting this error.What kind of environment are your drives in??
I have drives that may/do get some exposure to ammonia, this usually causes copper to oxidize rather fast and may be causing the issue that is your hypothesis.The drive model I have is a FC 102 and it has 3 ribbon/belt cables in it.I will try them one at a time and see what happens.Currently I have a drive disconnected from a motor and running. It was giving the earth fault alarm, I re-initialized the drive ( trying to re-zero the current sensors according to danfoss tech bulletin-10 common faults with the VFD). The drive is still giving the earth fault. I will try replacing one of the 3 cables at a time to see if I can isolate which one is giving me the grief. I will start with the one from the board with the current sensors.Thanks,Brent. Hi Nightex,I will give this a try. I have 15 66kW VFD's and I seem to keep getting this error.What kind of environment are your drives in??
I have drives that may/do get some exposure to ammonia, this usually causes copper to oxidize rather fast and may be causing the issue that is your hypothesis.The drive model I have is a FC 102 and it has 3 ribbon/belt cables in it.I will try them one at a time and see what happens.Currently I have a drive disconnected from a motor and running. It was giving the earth fault alarm, I re-initialized the drive ( trying to re-zero the current sensors according to danfoss tech bulletin-10 common faults with the VFD). The drive is still giving the earth fault. I will try replacing one of the 3 cables at a time to see if I can isolate which one is giving me the grief.
I will start with the one from the board with the current sensors.Thanks,BrentYes my danfoss VFD VLT 6000 (if I remember correctly) also works in amonia enviroment (compost farm). Once we had same problem on FC300 series, but I dont remmember what Ive done or maybe it just disappeared. Not so long ago there was same problem with another VLT 22kW, we replaced cables no problems till now. We also have 24x danfoss vlt 6000 55kW in amonia free enviroment now running about 10 years with few issues, and only one drive of 24 was with 14 alarm earth fault. Vry reliable equipment.
Problems with VFD ventilator in dust enviroment are common, you have to change ventilator bearings and capacitor. Good that these drives have internal overtemp. A common problem, especially with installations where there is one drive feeding multiple motors, is that the cables going from the drive to the motors can exhibit the properties of capacitance between them because of the steep rise time of the PWM pulses. The longer the circuit length the more likely that is to happen, but often times the manuals will only state that as the distance between the drive and motor. On multi-motor applications, that circuit length is multiplied by the number of motors. So if, for example, the maximum stated distance from drive-to-motor is 100m, but you are only 60m, you think you are fine, but in reality your CIRCUIT length is 120m.So what happens is that the capacitive charging current in that circuit APPEARS to the VFD protection algorithms to be a Residual Current Ground Fault, meaning Ix amount of current is flowing out, Ix-n is returning. The assumption in the algorithm is that n is current flowing to ground, when in reality it is just charging up the capacitor you have created in the conductors.The cure for that is a load reactor, because by adding inductance to the circuit closer to the VFD, you slow down the steep rise time of the PWM pulses and help reduce the capacitive effect in the cables.If it was working fine and suddenly began exhibiting this behavior, then look for something that has changed.
One thing that exacerbates this phenomenon is when people mess with the Carrier Frequency in the VFD so as to make the motors run 'quieter'. Rick and morty dvd ebay. Increasing the carrier frequency above 10kHz doesn't really make the motor stop whining, but it does move the sound frequency out of the range of human hearing. However at the same time, it will INCREASE the capacitive coupling effect in the circuit conductors.
Earth Fault and Ground Fault is intended to mean the same thing. I think Ground Fault is North American ad Earth Fault is probably everywhere else, certainly Europe. Drives built as 'worldwide' drives will usually say Earth Fault.How is it measured? The simplest description is that the current leaving the drive off of the positive rail of the DC bus is compared to the current returning on the negative rail of the DC bus. Within very small tolerances, if there is a difference, the conclusion is drawn that some of the current that went out there to the motor didn't come back!
As in leakage to ground! This difference monitoring creates the Earth Fault.Unfortunately, there are numerous complexities that can make nuisance faulting a big headache. That's why the fault can be turned off in Group 30 Parameter 17.I am not a drive repair person or a drive designer so the internals are not my strong suit. Having said that, externally, the drive Earth Fault detection works best when the incoming AC power is voltage balanced to ground and referenced to ground. That would be a grounded wye or star power source. Imbalance leads to false faulting due, as I am told, to capacitance between the two DC bus rails and the drive frame (which is grounded) causing imbalanced currents in the DC bus rails. Further complicating matters are EMI and RFI filter networks that are mandated by stringent European laws.
Earth Fault Definition
These filter networks must contact the drive chassis ground and, again as I am told, try to pull the DC bus into balance with ground. Ella mai down mp3 download. If the supply is not balanced or is floating, false faulting results and, in some cases, the filter networks burn up. ABB states in their installation manuals that these networks must be disconnected from ground on floating and imbalanced supplies to avoid drive damage. I have seen grounded delta power cause ground/earth faulting, too. I have seen ground/earth faults caused by large DC drives on the same power grid.
These commutation notches will fry those european filters on VFD's. My company had to deal with this a bit and we found that removing the european filter and using a 3% input reactor eliminated false tripping. This is FLOATING power with a high impedance grund fault detection system.If you have a long cable run and the carrier freq is too high, this sometimes manifests as ground faults. Anytime I have more than 50 feet of cable I make a practice of setting the carrier to 2K or the lowest the drive will program to when carrier freq selection is fixed.I have encoundered cases where a meggar test said the cable and motor insulation was fine but the drive tripped sporatically on ground fault. This was a new PWM drive replacing an old VVI that had no grounding issues.
A hi-pot of the motor and cable showed excessive leakage current at 1500 volts. The electrician said a portion of the cable had been pulled during a turn around. He found two of the cables chaffed. They were replaced and things worked fine.These are a few of the problems I have encountered over the years.
A is to control the speed of an AC motor. It is not intended to be used as a circuit protection equipment in the case of a ground fault. The installation of a variable frequency drive to a correctly protected circuit will not change the effectiveness of the protection.If a ground fault occurs in the motor circuit of a variable frequency drive then the variable frequency drive overcurrent protection will remove its output in a very short time, generally less than 1 ms. This function is built in to all variable frequency drives in order to protect them from damage caused. This is however only internal variable frequency drive protection and is not intended as general circuit protection or as personal protection.The variable frequency drive internal protection uses power semiconductor devices and complex electronic circuits to fulfill this function.
Single phase variable frequency drive can convert from single phase input to three phase output, but the maximum output voltage is equal to input voltage. In the case, you may need a transformer. The.The VFD manufacturer did additional research to identify some probable causes. The contractor needed to provide a proper earth ground, ground the controller and the motor to this proper earth ground.If you are running the system with variable frequency drive then you should precharge the tank to 65% of cutoff pressure. If you have a traditional booster system running with pressure switch the.This article have a study of the wireless group control system with variable frequency drive (VFD) applied in a Chinese plantation irrigation system. China is a fresh water resources scarce country.I know that you can use inverter duty motor with 10:1 ratio. While standard motor 2:1.
I know VFD (variable frequency drive) operating range for positive displacement Pumps. Positive displacement.