VFD Motor Overspeed 1

[TugboatEng]

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?

 

[RedSnake]

/A

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

 

[TugboatEng]

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.

 

[RedSnake]

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.

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

 

[RedSnake]

Is this the right manual ?

https://literature.rockwellautomation.com/idc/groups/literature/documents/pm/750-pm001_-en-p.pdf

BR A

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

 

[RedSnake]

From above manual

BR A

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

 

[RedSnake]

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

 

[TugboatEng]

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.

 

[RedSnake]

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

 

[RedSnake]

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

 

[TugboatEng]

 

[RedSnake]

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

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

 

[RedSnake]

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

 

[TugboatEng]

Motor Options Config 1001 1000 1111 x111

Flux Up Time 0.2419 secs

Auto tach switch 0

Noise Filter is 3 - 50R/S

 

[RedSnake]

Par 40 Motor Options Config 1001 1000 1111 x111

Bit 0 “Zero TrqStop” – Configures stopped condition when in torque mode. [highlight #8AE234]1 = wait for zero torque before shutting off drive output.[/highlight]
Bit 1 “Trq ModeStop” – Configures stopping behavior when in torque mode.[highlight #8AE234] 1 = switch to speed mode[/highlight]
Bit 2 “Trq ModeJog” – Configures jogging behavior when in torque mode. [highlight #8AE234]1 = switch to speed mode[/highlight]
[highlight #EF2929]
Bit 3 “EnclsTrqProv” – Enables encoderless mode when using the torque prove function.[/highlight]

Bit 4 “Mtr Lead Rev” – Reverses the phase rotation of the applied voltage, effectively reversing the motor leads. [highlight #8AE234]1 = Reversed[/highlight]
Bit 5 “Reflect Wave” – Enables reflected wave voltage protection for long motor cables.[highlight #8AE234] 1 = Enabled[/highlight]
Bit 6 “RS Adaption” – Adapts for changes in motor stator resistance due to motor temperature. Active only in FV motor control mode with feedback.[highlight #8AE234] 1 = Enabled[/highlight]
Bit 7 “PWM Type Sel” – Configures 3 Phase / 2 Phase switching of the power devices. [highlight #8AE234]1 = Full time 3 phase modulation (no switchover)[/highlight]

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. [highlight #8AE234] 1 = Enabled[/highlight]

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. [highlight #8AE234] 1 = Enabled[/highlight]
Bit 13 “Common Mode” – Enables the common mode reduction feature. See Parameter 41, Common Mode Type, for common mode type selection.
[highlight #EF2929]Bit 14[/highlight]
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. [highlight #8AE234]1 = Enabled (0.0 second ramp time prevented)[/highlight]


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