VFD(VSD) on sluice gates 2

[CuriousElectron]

Hi All,
I had a question - I'm seeing Variable frequency drives or variable speed drives being used on sluice gates (vertical slide gates) to drive gate motor actuator. Why is the reason behind it? Why not use a standard FVNR starter instead. These gates are rated at 3 HP to 5 HP. I see they are used in project sites where 3 phase is not available, so those drives convert 1 phase 120VAC into 3 phase 240V. Is that the main reason, to be able specify a 3 phase motor instead of a 1 phase motor and have better means of control& longevity of the electric actuator?
Thank you.
EE

 

[waross]

Three phase on a VFD versus a single phase motor;
Less points of failure on a three phase motor compared to a single phase motor.
Lower starting surge with a VFD.
More breakaway torque to overcome sticktion with a three phase motor compared to a single phase motor.
Even more breakaway torque to overcome sticktion with the torque boost feature of the VFD.

 

[CuriousElectron]

Thank you for the explanation, Mr.waross!

 

[jraef]

Also, simple reversing, which is more complex with single phase motors. With a VFD on a 3 phase motor, you just give it a reverse command, no contactors involved.

With Sensorless Vector Control, which is standard on most VFDs now, you can get full torque at the outset, you no longer need to use torque boost. But better than that, you can get a soft start from it, so less wear and tear on the gearbox of the weir gate.

 

[Doaa Hamdy]

Great question! Here’s why VFDs are preferred for sluice gates:

Phase Conversion: VFDs can convert single-phase 120VAC into three-phase 240V, allowing the use of more efficient and reliable three-phase motors in locations where three-phase power is unavailable.

Speed and Torque Control: VFDs offer precise control over motor speed, making it ideal for controlling gate positions. They also provide higher breakaway torque to overcome sticktion when compared to single-phase motors.

Soft Start: VFDs reduce inrush current at startup, minimizing electrical and mechanical stress, and extending the life of both the motor and actuator.

Torque Boost: The torque boost feature in a VFD further enhances breakaway torque, ensuring smoother and more reliable operation of the gate.

In short, VFDs provide better control, efficiency, and motor protection, making them the ideal choice for this application.

 

[LittleInch]

Great question! Here’s why VFDs are preferred for sluice gates:

Phase Conversion: VFDs can convert single-phase 120VAC into three-phase 240V, allowing the use of more efficient and reliable three-phase motors in locations where three-phase power is unavailable.

Speed and Torque Control: VFDs offer precise control over motor speed, making it ideal for controlling gate positions. They also provide higher breakaway torque to overcome sticktion when compared to single-phase motors.

Soft Start: VFDs reduce inrush current at startup, minimizing electrical and mechanical stress, and extending the life of both the motor and actuator.

Torque Boost: The torque boost feature in a VFD further enhances breakaway torque, ensuring smoother and more reliable operation of the gate.

In short, VFDs provide better control, efficiency, and motor protection, making them the ideal choice for this application.

AI generated?

 

[waross]

Phase Conversion: VFDs can convert single-phase 120VAC into three-phase 240V

Is this the part that worries you, LittleInch?
An inverter is able to develop any phase angle.
Three sections, developing 120 Volts at 120 electrical degree intervals will provide 208 Volt three phase. A little distortion of the PWM, RMS wave form will get 240 Volts three phase.
That said, it may still be AI generated. (Or A-1, depending on how you vote. grin)

 

[wcaseyharman]

I could see adding VFDs on single phase systems to allow for 3 phase motors would be a good practice. The max torque on a gate would be closed with the full force of water behind it, and single phase motors don’t have great starting torque. I have a feeling a smaller VFD and 3 phase motor would be significantly cheaper than installing a single phase motor large enough to overcome the starting torque of the gate.
I work at a company that has two hydroelectric dams and haven’t heard of any push yet to add VFDs to spillgate motors in the industry. We are actually currently reviewing designs to redo the entire top of dam including 12 new spillgates and spillgate mechanisms and there has been no suggestion thus far of using VFDs, but working at a hydroelectric dam we do have plenty of 3 phase power…