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Old December 6th, 2017, 08:10 AM   #1
qsubhani
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PowerFlex 700

I am having a problem to find out the cause of dropping our power flex 700 series drive. We had an issue a month ago that drive burnt out and we were replaced with new drive.
Using the old cassette from old drive, HIM module and Controlnet Card, we were able to run the drive. As well as I verified all the parameters that we have it found all ok.
Problem:
From last two weeks we noticed that drive drops to 20 %(12HZ) and back to normal by itself .
This drive only has a provision to RUN from BAS (Building Automation System) and it's running on
Controlnet Network.
Following is the Rung for starting of AH unit.


Speed Reference Parameters:
Parameter# 90= DPI Port 1 value=18
Parameter# 91= DPI Port 5 value=22
Parameter# 100= 100
Parameter# 101= 5.0
Parameter# 102= 10.0
Parameter# 103= 20.0
Parameter# 104= 30.0
Parameter# 105= 40.0
Parameter# 106= 50.0
Parameter# 107= 60.0
Process PI:
Parameter# 126 = Set Point value =0
Parameter# 128 = Analog IN 2 value =2

Please advise how to trouble shoot.
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Old December 6th, 2017, 11:07 AM   #2
Ken Roach
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Welcome to the PLCTalk forum community !

How long does the drive remain at 12 Hz ? What sort of load is it driving, and are there any physical changes to the load ?

Have you put in a logic trap to be sure that the Reference value is not actually changing ?

Is the low frequency exactly 12 Hz, or is that an approximate number ? 12 Hz isn't one of the Preset or Minimum frequency values, so it has to be coming from some other function of the drive, or you're only seeing it at some point while the drive is decelerating or accelerating past that value.

There are parameters that will allow you to monitor the source of the Command.

DPI Logic Result (Parameter 271) will show you which devices are telling the drive to choose a reference.

Reference Owner (Parameter 292) will show you which device is actually giving the reference to the drive.

I've seen drives "randomly" switch to a Preset Speed when there is electrical noise present and unused wires connected to the Digital Inputs. I set my Digital Inputs to "no function" to prevent this, and/or jumper them to DC Common to keep them False.
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Old December 6th, 2017, 02:17 PM   #3
Lovell
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Check your IO card and see if anything is wired to Digital In 4.

If so check P364 - default value is Speed Sel1. If P364 is '15' Speed Sel 1 then speed will change if Digital In 4 is true. You can change it to 0 (not used) if you don't want this action.
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Old December 6th, 2017, 07:45 PM   #4
jraef
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If all of that fails, when it is doing this, check the value of Parameter 210, bit 10 to see if the drive is going into Current Limit. Current Limit will override your speed command in an attempt to keep the current under control. If it is going into Current Limit and dropping the speed to 12Hz, next check the settings of parameter 148 and 147. Someone may have inadvertently set the CL to a really low value, not understanding what it means. The factory default setting is the Drive's maximum current setting, 150%. If the motor current is trying to jump to over 150% while the machine is running, something is wrong with your load, such as something jamming. Given that the previous drive burned itself out, that problem may have been what cause it and still exists.

Last edited by jraef; December 6th, 2017 at 07:48 PM.
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Old December 7th, 2017, 07:44 AM   #5
qsubhani
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Hi Ken,
Thanks for your reply. I am trying to provide maximum information that you are requested.
How long does the drive remain at 12 Hz ? What sort of load is it driving, and are there any physical changes to the load ?
I checked with trend and speed drops almost 3 minutes and goes back to normal. Bear in mind that we put the speed on manual mode from BAS and still drops to 12HZ(minimum speed).There is no such load changes but I verified from field that actually motor goes to minimum speed .
Have you put in a logic trap to be sure that the Reference value is not actually changing?
I didn't get your point for logic trap. I don't have access to go online and checked the program but I can request the concerned department for specific point of trouble shooting.

Is the low frequency exactly 12 Hz, or is that an approximate number? 12 Hz isn't one of the Preset or Minimum frequency values, so it has to be coming from some other function of the drive, or you're only seeing it at some point while the drive is decelerating or accelerating past that value.
Yes I verified from field that speed goes to 12HZ (minimum speed )parameter#81 set at 12HZ and 12HZ is =20% of our BAS scale(0 to 100%)

There are parameters that will allow you to monitor the source of the Command.
We are using DPI port5 (connected on controlnet) for speed reference. I checked speed reference and parameter
Parameter# 90= DPI Port 1 value=18
Parameter# 91= DPI Port 5 value=22


DPI Logic Result (Parameter 271) will show you which devices are telling the drive to choose a reference.
Parameter# 91= DPI Port 5 value=22



Reference Owner (Parameter 292) will show you which device is actually giving the reference to the drive.
Reference Owner Parameter set= 1(Digital Input 1)

I've seen drives "randomly" switch to a Preset Speed when there is electrical noise present and unused wires connected to the Digital Inputs. I set my Digital Inputs to "no function" to prevent this, and/or jumper them to DC Common to keep them False.
My Digital Inputs are
Parameter# 361= 4(STOP)
Parameter#362=15(Speed Select1)
Parameter#363=18(Auto/Manual)
Parameter#364=0(Not Used)
Parameter#364=0(Not Used)
Parameter#365=16(Speed Select2)
Parameter#366=1(Enable)
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Old December 7th, 2017, 08:00 AM   #6
qsubhani
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Hi Loveall,
My Digital Input 4 are not in used and value is set to 0
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Old December 7th, 2017, 08:18 AM   #7
qsubhani
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Hi Jraef,
I didn't get a chance to check the drive status bits because it happens for a while and goes back to normal. Anyway I verified at normal running that BIT 0(ready),1(Active),2(Running)and 13(DPI at 500K) are active .
Parameter # 147 is set= 0 and we are not using this current limit option.
For my understanding when load sudden change it has to trigger first Motor overload.
My Motor control parameters are
Parameter#40=Induction
Parameter#41=575.0 VAC
Parameter#42=15.3 Amps
Parameter#43=60.0 HZ
Parameter#44=1780 RPM
Parameter#45=15.00 HP
Parameter# 46=0 Horsepower
Parameter# 47=20HZ
During running condition motor runs @44.8HZ and taking current 8.8A
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Old December 7th, 2017, 10:11 AM   #8
osmanmom
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i not familiar this vfd just rough read from manual

i guess it normal behavior because this is PI mode
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Old December 7th, 2017, 10:19 AM   #9
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With 12Hz being your minimum speed setting, I'd guess then that the drive is losing its speed reference command and dropping to the minimum speed, because you have it programmed that way. I no longer have my manual with me, but there is a parameter someplace where you tell the drive what to do on a loss of communications. One option is "Run at Minumum", another is "Maintain Previous Speed Command", and I think it offers a "Fault and Shut Down" option. If Run at Minimum is what you want, then you need to find out why you are dropping out your COMM signal.
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Old December 7th, 2017, 10:39 AM   #10
osmanmom
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as jref mention
Attached Images
File Type: jpg loss.JPG (89.0 KB, 44 views)
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Old December 7th, 2017, 10:59 AM   #11
qsubhani
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Hi Jraef,
I checked the parameters under communication module and cant find the parameters that says what to do under loss of communication.
I believe that
If the drive can't talk to the 20-Comm-D over DPI, it gives a DPI comms fault and an "8x" error code.

If the drive can talk to the 20-COMM-D but the 20-COMM-D can't talk over Device Net to the scanner, the drive faults on a Network communication fault and gives an "7x" error code.

Is there any way I can find that problem is in our hardware(Only one selector switch of AUTO/MANUAL)installed on local drive panel.That gives the signal to drive that I am on Auto and drive than can RUN through control net.
How I can be make sure that NO loss of communication occurred when motor goes to minimum speed.
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Old December 7th, 2017, 11:13 AM   #12
qsubhani
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I am using Powerflex 700 series drive and the list of parameters you attached it its not the parameters list of Powerflex700 model series.
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Old December 7th, 2017, 01:26 PM   #13
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121 listed above is a fault code.

The Loss of Comms parameter you are looking for is in the ControlNet card, not the VFD itself. Parameter Number 10. Your first post listed a ControlNet card, but your listed a 20-comm-d card in post 11. For either card, the parameter is the same. The 121 error should be present if you are having comm issues. You can use the adapter diagnostics listed in the comm card manual. In the 20-comm-d manual it's Chapter 7.

http://literature.rockwellautomation...m002_-en-p.pdf
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File Type: jpg Shot1.jpg (59.7 KB, 4 views)

Last edited by SledDog; December 7th, 2017 at 02:21 PM.
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Old December 7th, 2017, 02:18 PM   #14
qsubhani
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Hi SledDog,
Thanks for clarification.I have to check if any fault present at the time when motor goes to minimum speed.
Can I see these parameters through HIM module and can I do change the parameter during running condition without any interruption.
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Old December 7th, 2017, 03:20 PM   #15
Lovell
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It looks like Parameter 365 may be the source of your problem. If something is wired to Digital In 5 then speed would change when that input is true. You can set P365 to 0 as a test to see if that solves the problem.
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