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VFD Motor Overspeed

VFD Motor Overspeed

VFD Motor Overspeed

(OP)
I am having an issue with a winch motor operated by VFD. During powered inhaul the motor is tripping on overspeed. The max frequency and overspeed trips are set correctly. I don't see how it's possible for the VFD to drive the motor at excessive speed. Is it possible for the shaft encoder to output a faulty speed signal that is high?

RE: VFD Motor Overspeed

Can you check the speed independently of the shaft encoder?
Is this a new installation or a problem that has developed over time in service?

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

RE: VFD Motor Overspeed

(OP)
It's not clear when the problem began. The crew has been working around it.

To get the motor speed? Now you're asking the hard questions. I guess I could pull the rotary coupling for the clutch and put a nipple to extend it so I can use an optical tach. I don't get access to the boat very often for troubleshooting.

To make the problem worse, the Drive Explorer file in the HMI is corrupt and I didn't bring my laptop.

RE: VFD Motor Overspeed

If you have a stroboscope, you can check the speed and actually see the rotor stationary at its speed. It's what I do when I don't have access to put a tach.

Muthu
www.edison.co.in

RE: VFD Motor Overspeed

(OP)
This is a TENV motor driving an epicyclic gear turning a sprocket in an enclosed chaincaee.

RE: VFD Motor Overspeed

Doesn't it have a fan at the back end?

Muthu
www.edison.co.in

RE: VFD Motor Overspeed

TENV. Bummer. Any key projection at the back of the coupling?

Muthu
www.edison.co.in

RE: VFD Motor Overspeed

(OP)
The winches with captains have shaft brakes so I can pull the brake housing cover to expose the shaft. No capstain on this one. This winch has a rotary coupling for the pneumatic clutch. I think that's my only access though that may be after the clutch.

I'm in contact with the vendor and they have me chasing limit switches that indicate the park position of the control levers but I feel the VFD shouldn't be capable of driving a motor in to an overspeed condition?

RE: VFD Motor Overspeed

If you can put a paint mark in any of the motor rotating part before the clutch, a strobe could work. I say strobe because you can actually see if the rotating component is swinging around the base speed.

Muthu
www.edison.co.in

RE: VFD Motor Overspeed

Noise on the encoder cable will cause this. Make sure the connections are good and the shields are all intect and connected properly.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

RE: VFD Motor Overspeed

Will the clutch slipping mess up the encoder?

Muthu
www.edison.co.in

RE: VFD Motor Overspeed

(OP)
The encoder is directly mounted to motor shaft, no clutch involved.

Ahah! Got to the boat today. There is a cover on the encoder end. Now if I only had a tach.

RE: VFD Motor Overspeed

Are they pulling line out with engine power? (Come in close to attach the tow line and then motor away to pull slack.)
They may indeed be running the motor over-speed.
But;
If the over-speed is NOT accompanied by over current, then suspect an issue with the encoder system.

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

RE: VFD Motor Overspeed

(OP)
The overspeed is being driven entirely by the motor. Motor is pulling in a slack line when it overspeed trips. Current is low because load is low.

I need to add, this is in render/recover mode which is intended to maintain a constant tension on the line. The trip only occurs in the in-haul.

RE: VFD Motor Overspeed

Your drive may be configured to maintain too much tension.
If the drive is increasing speed trying to maintain a preset tension, that may drive the motor over-speed.
It is probably worthwhile to look at that parameter.

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

RE: VFD Motor Overspeed

(OP)
It does it even in minimum tension. The drive is also capped at 100hz, 2000 rpm. Overspeed is set for 3000 rpm.

RE: VFD Motor Overspeed

What kind of encoder is it ?
A tachometer generator or a impulse encoder ?
With a tachometer generator it would always give a lower value if broken.
With a impulse encoder it could give a higher value if broken but not lightly 1,5 times as much.
Then it would be more reasonably that it is set up wrong in the VFD.
Wrong code gray vs binary or the wrong amount of bits with or without sign or something like that.

Best Regards A

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

RE: VFD Motor Overspeed

(OP)
Ahh, you guys/gal were right. It does appear to be a settings issue. Overspeed setpoint is only 10 rpm different from max speed and after only 2ms duration. I finally figured out how to get in to the parameters list. There is a handy little HMI on the drive itself.

RE: VFD Motor Overspeed

And do you have the exact ordering code ?



/A

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

RE: VFD Motor Overspeed

pc2 thumbsup2

/A

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

RE: VFD Motor Overspeed

(OP)
I have had access to two vessels with the same VFD (AB Powerflex 753) and the overspeed parameters match so this problem is still open.

RE: VFD Motor Overspeed

Do you have any possibility to show a parameterlist?
Overspeed setpoint is only 10 rpm different from max speed.
And max speed was to 3000 rpm or was that overspeed?
and after only 2ms.

2 ms is nothing!
I have a hart time realizing why the time is so short and even a harder time understanding what
the consequences are with a bit of over speed in this situation. ponder

Normally you choose the speed you want the motor to have and the incremental encoder tells the system that the speed is kept.
And you have a speed "window" that you can tolerate.
And when that is not kept you usually get a alarm that is called "Following Error"
If you go 1000 rpm or 1010 rpm what happens?

Best Regards Anna

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

RE: VFD Motor Overspeed

From above manual









BR A

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

RE: VFD Motor Overspeed

During powered inhaul, does that mean that you pull the line in?
Is it with load?
Without load?
And when you do this is the motor going in forward or reverse?
There are different parameter settings for forward and reverse, that effects the alarm 25 OverSpeed Limit.

BR A

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

RE: VFD Motor Overspeed

(OP)
The trip happens while pulling the line in unloaded. I don't know if it is plus or minus direction but the drive is configured symmetrically.

This is from the manual:



We are using vector control.

RE: VFD Motor Overspeed

Can you access this status word on the panel ?
If so you should be able to see the motor direction in bit 2 and 3 if you test drive it.



Best Regards A

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

RE: VFD Motor Overspeed

If I am looking in the right manual there many different types of vector controls.
So if it possible to look at parameter 35 in the panel it would help.


/A

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

RE: VFD Motor Overspeed

(OP)

RE: VFD Motor Overspeed

35 Induction FV (3) – Induction motor, flux vector control mode thumbsup2

Inverters with this many parameters usually have a read out option on the panel so you can go through the parameters that are changed from factory settings.
It is almost impossible to give advice without the basic settings at hand.
There seems to be a function that is called Automatic Tach Switchover, what governs it I do not know but it is used to use different feedback sources or filters, if the encoder is broken and this is used it can start using other parmetersets then it usually uses.









Par 635


BR A

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

RE: VFD Motor Overspeed

Some parameters to look at for this function.



Par 953
Bit 7 “Overspd Lmt” – When set, indicates that a F25 “OverSpeed Limit” fault has occurred.
This is a non-configurable fault. An overspeed condition results when the motor speed falls outside of its normal operating range.
The limits of this range are established by P521 [Max Rev Speed] - P524 [Overspeed Limit] = (lower limit) and P520 [Max Fwd Speed] + P524 [Overspeed Limit] = (upper limit).
In flux vector control mode or scaler control mode with encoder, the motor speed used is a 2 msec averaged value of P131 [Active Vel Fdbk].
The overspeed condition must exist for at least 16 milliseconds before it causes a fault to occur.

Parameter 40 och 44 can also be interesting to know.
Parameter 2 would tell you if witch way the motor runs when inhauling.

/A

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

RE: VFD Motor Overspeed

(OP)
Motor Options Config 1001 1000 1111 x111

Flux Up Time 0.2419 secs

Auto tach switch 0

Noise Filter is 3 - 50R/S

RE: VFD Motor Overspeed

Par 40 Motor Options Config 1001 1000 1111 x111



Bit 0 “Zero TrqStop” – Configures stopped condition when in torque mode. 1 = wait for zero torque before shutting off drive output.
Bit 1 “Trq ModeStop” – Configures stopping behavior when in torque mode. 1 = switch to speed mode
Bit 2 “Trq ModeJog” – Configures jogging behavior when in torque mode. 1 = switch to speed mode

Bit 3 “EnclsTrqProv” – Enables encoderless mode when using the torque prove function.


Bit 4 “Mtr Lead Rev” – Reverses the phase rotation of the applied voltage, effectively reversing the motor leads. 1 = Reversed
Bit 5 “Reflect Wave” – Enables reflected wave voltage protection for long motor cables. 1 = Enabled
Bit 6 “RS Adaption” – Adapts for changes in motor stator resistance due to motor temperature. Active only in FV motor control mode with feedback. 1 = Enabled
Bit 7 “PWM Type Sel” – Configures 3 Phase / 2 Phase switching of the power devices. 1 = Full time 3 phase modulation (no switchover)

Bit 8 “AsyncPWMLock” – Configures Synchronous / Asynchronous switching of the power devices. 0 = Automatically changes between synchronous and
asynchronous.
Bit 9 “PWM FreqLock” – Configures switching frequency of the power devices while in FV motor control mode without feedback. 0 = switching frequency
automatically reduces to 2 kHz at low speeds (best performance)
Bit 10 “DB WhileStop” – Enables operation of the dynamic brake transistor while the drive is stopped. 0 = Disabled
Bit 11 “Elect Stab” – Enables stability control for Sensorless Vector and V/Hz motor control modes. 1 = Enabled

Bit 12 “Xsistor Diag” – Enables power transistor diagnostic test at each start command. Recommended to set to Disabled if an output filter is installed with the drive. Refer to publication PFLEX-AT002 for additional information. 1 = Enabled
Bit 13 “Common Mode” – Enables the common mode reduction feature. See Parameter 41, Common Mode Type, for common mode type selection.
Bit 14
Bit 15 “Jerk Select” – Limits the rate of change to the velocity reference for improved current limiting. This setting applies only to Sensorless Vector and V/Hz motor control modes. 1 = Enabled (0.0 second ramp time prevented)


You might want to look at bit 12 and bit 15.
bit 15 is what waross was taking about earlier, it smoots the speed in the corners when going from acc/deacc to continues speed this makes it run without "pulls and jerks" which can create "folloing errors / overspeed faults"





BR A

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

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