VFD with communication fault.

[LHarrington]

Good afternoon,
We are working on a 200hp compressor with a VFD from Cutler Hammer. We have had intermittent VFD COM FAULTS showing up and shutting us down. We have communicated with the manufacture and they are stating my ac voltage at the I/O module could be causing the problem, which is riding at 25 to 27 VAC. They are suggesting I change the primary taps on the main control transformer from H1 and H4 to H1 and H5. their goal is to reduce the secondary voltage on main control trans to lower than 120 VAC in turn will reduce the 25 to 27 VAC to around 22 to 24 VAC which the I/O module is requiring. Has anyone else had this problem or think this is a legitimate approach a solution? The compressor in question is one of two in a series and they talk all day long to determine who needs to be the trim machine and who in standby. The equipment has the ability to see fault and log them, which has been recording errors but has not shut me down yet today. However, I would prefer to correct the problem so I can relax. We have even had a situation where the display screen has locked up and you have to cycle the power to recover. In comparison to the identical machine, all of the voltages are the same but it does not have this problem.

Thanks for your time
LHarrington

 

[nakulak]

In comparison to the identical machine, all of the voltages are the same but it does not have this problem.

Thanks for your time
LHarrington

all of the voltages are the same, but the manuf. insists that the voltage on the one is causing a problem ? doesn't sound likely, but it sounds like you are going to have to put the 24 volts proper on the machine so these guys will shut up and fix the problem ? (jmho)

 

[weressl]

Good afternoon,
We are working on a 200hp compressor with a VFD from Cutler Hammer. We have had intermittent VFD COM FAULTS showing up and shutting us down. We have communicated with the manufacture and they are stating my ac voltage at the I/O module could be causing the problem, which is riding at 25 to 27 VAC. They are suggesting I change the primary taps on the main control transformer from H1 and H4 to H1 and H5. their goal is to reduce the secondary voltage on main control trans to lower than 120 VAC in turn will reduce the 25 to 27 VAC to around 22 to 24 VAC which the I/O module is requiring. Has anyone else had this problem or think this is a legitimate approach a solution? The compressor in question is one of two in a series and they talk all day long to determine who needs to be the trim machine and who in standby. The equipment has the ability to see fault and log them, which has been recording errors but has not shut me down yet today. However, I would prefer to correct the problem so I can relax. We have even had a situation where the display screen has locked up and you have to cycle the power to recover. In comparison to the identical machine, all of the voltages are the same but it does not have this problem.

Thanks for your time
LHarrington

I deal a lot with C-H that now is Eaton Electric. The response you're getting is not what their Corporate Policy endorses, so go after them.

Did they state in the manual the voltage limits? What they claim is much tighter than common acceptable limits in the industry. If they have not stated the limit, it is their problem. Deman that they come out, analyze the problem, prepare a report and give you a timetable driven solution.

 

[LHarrington]

No there is no min or max voltage spec. for this portion of the equipment We have every intention of putting the responsibility on them however it's my house and our efficiency is what's effected. Not to mention my piece of mind that being toyed with. I am just trying to check their suggestion one because of the timing with the holiday and the risk of being pushed off is huge, secondly it is up to me to have the answer and solutions.

LHarrington

 

[Loffgren]

Vfd

Vfd

I work with Allen Bradley PowerFlex7- VFD class every day. I had the same issue, and i had to update the firmware within the drive. On the AB website they have a controlflash software that works through there serial device. Call manufactuer and ask if they have a software revision

 

[ramsy]

Voltage spikes and transients are frequently described as cause for a variety of drive failures, and line reactors are described as one the solutions. If line surges coincidently stopped just before a firmware update, the next transient may burn up that theory.

 

[Krim]

Good afternoon,
We are working on a 200hp compressor with a VFD from Cutler Hammer. We have had intermittent VFD COM FAULTS showing up and shutting us down. We have communicated with the manufacture and they are stating my ac voltage at the I/O module could be causing the problem, which is riding at 25 to 27 VAC. They are suggesting I change the primary taps on the main control transformer from H1 and H4 to H1 and H5. their goal is to reduce the secondary voltage on main control trans to lower than 120 VAC in turn will reduce the 25 to 27 VAC to around 22 to 24 VAC which the I/O module is requiring. Has anyone else had this problem or think this is a legitimate approach a solution? The compressor in question is one of two in a series and they talk all day long to determine who needs to be the trim machine and who in standby. The equipment has the ability to see fault and log them, which has been recording errors but has not shut me down yet today. However, I would prefer to correct the problem so I can relax. We have even had a situation where the display screen has locked up and you have to cycle the power to recover. In comparison to the identical machine, all of the voltages are the same but it does not have this problem.

Thanks for your time
LHarrington

Aren't your comm cables shielded to protect the data from EMI ?
It sounds to me like you aren't shielded properly (only grounded at one end)or there is a software problem going on.Check the revision date of the software and hardware for compatibility.They always like to place the fault on the electrician or electrical apparatus as opposed to the factory cables and/or software compatibility/revision issues!
Carl

 

[stickelec]

I'm not familiar with the Eaton/CH VFD but I am curious about a few things if you have a moment:

Assuming the comm is RS485:
1) What is the Baud Rate?
2) How many Nodes on the network?
3) Is the network ring, star, or is it a mix?
4) Exactly were is this device located in the layout of the network?
5) Are there Terminating Resistor(s) present and if so where, and what are the values?
6) Is the cable 2-conductor w/ 100% shield, what is the length/distance and what is the wire-gauge?
7) Is the cable continuous or is it spliced or otherwise terminated except at the Node(s)?
8) Is this a new problem or has it always existed to some extent?
9) Has the troublesome comm-card ever been replaced? Has it been pulled and re-inserted?
10) Could you give some detail on exactly what the Fault Code is saying?
11) Have you lifted the single-point of connection for the Shield and checked for continuity to ground?
12) Could you describe the "point of grounding" for the Shield, what else is grounded there, and describe the "copper-path" from there to the facility Grounding system?
13) Does this comm-cable run in Tray in close proximity to hi-current AC conductors?

 

[johnny watt]

I would expect that the semiconductors are looking for 24VDC and it would be created with a 3-pin regulator
like an LM7824 and 3 extra AC volts supplying the regulator would be irreverent.
Locked up display?hmm
Software/firmware
dirty/ripple/parasitic oscillations on power supply
lack of watchdog circuit in design or not functioning
obviously, possibly an RFI problem. Maybe cable spec. problem, shielding landing problem. (a faraday shield should only land on one end)

 

[chaterpilar]

IMO..the ac voltage (diff) 3-4 volts will not make any difference...the EMI/RFI seems to be the more possible cause...

What is the type of cable used between the VSd and motor?

How far is this cable away from comm. cable...( 300 mm clearance is desirable)

If you are having screen/armour on the cable between VSd and motor ensure it is bonded to ground at both ends.

Signal cables shield should be bond to ground at one end only.

Hope it helps...

 

[Krim]

I'm not familiar with the Eaton/CH VFD but I am curious about a few things if you have a moment:

Assuming the comm is RS485:
1) What is the Baud Rate?
2) How many Nodes on the network?
3) Is the network ring, star, or is it a mix?
4) Exactly were is this device located in the layout of the network?
5) Are there Terminating Resistor(s) present and if so where, and what are the values?
6) Is the cable 2-conductor w/ 100% shield, what is the length/distance and what is the wire-gauge?
7) Is the cable continuous or is it spliced or otherwise terminated except at the Node(s)?
8) Is this a new problem or has it always existed to some extent?
9) Has the troublesome comm-card ever been replaced? Has it been pulled and re-inserted?
10) Could you give some detail on exactly what the Fault Code is saying?
11) Have you lifted the single-point of connection for the Shield and checked for continuity to ground?
12) Could you describe the "point of grounding" for the Shield, what else is grounded there, and describe the "copper-path" from there to the facility Grounding system?
13) Does this comm-cable run in Tray in close proximity to hi-current AC conductors?

I would think that #9 was tried before posting, but yes,since it is a 'comm fault' I'd check all the basics pertaining to the actual communications setup first of all. It could be a parameter setting has been accidentaly changed, a comm board has gone bad or simply a loose jumper .
Carl :smile:

 

[LHarrington]

Good news,
Correcting the voltage to the I/O module has thus far corrected our problem, when we arrived on Saturday the unit in question was logging error just sitting there. We disconnected power and re-tapped the Trans to H1 and H5 giving us a lower voltage on the secondary. This provided a lower voltage to the module between the 22 and 24 volts the manufacture want and we have had no error. Unit has been setting in stand by all weekend with no errors. Prior to the change it was logging errors at least every 5 minutes or so. Now I have created a second thread for AC to DC converters so I can create a more reliable voltage because our line will drop during the hot summer month and I am sure I will be looking at the low side then.

LHarrington

 

[Krim]

Good news,
Correcting the voltage to the I/O module has thus far corrected our problem, when we arrived on Saturday the unit in question was logging error just sitting there. We disconnected power and re-tapped the Trans to H1 and H5 giving us a lower voltage on the secondary. This provided a lower voltage to the module between the 22 and 24 volts the manufacture want and we have had no error. Unit has been setting in stand by all weekend with no errors. Prior to the change it was logging errors at least every 5 minutes or so. Now I have created a second thread for AC to DC converters so I can create a more reliable voltage because our line will drop during the hot summer month and I am sure I will be looking at the low side then.

LHarrington

Keep us informed as to whether changing the transformer taps was all that was needed to resolve the comm problem with your CH/EATON VFD.
Carl

 

[LHarrington]

I sure will but as of right now the compressor has been through several cycle and has had no problems. In the recent past it wasn't able to do this with out logging errors or crashing and forgetting who it was.
I'm not convinced just yet.

LHarrington