Film-Tech Forum ARCHIVE: Urgent...Variable speed motor/controller

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Posted by Anhtu Vu (Member # 7689) on 10-28-2019, 01:04 PM:

I will be installing 2 simplex 35 mm projectors soon. I need to replace the old variable speed motor/controller. Advice?

I'm located in Montreal.

Posted by Julian Antos (Member # 5497) on 10-28-2019, 04:57 PM:

To start, you'll need a three phase motor and an inverter/variable frequency drive. The motor needs to be "inverter duty" or you will wear it out prematurely.

Eaton and Lense (found in Kinotons) are both reliable VFDs for this purpose. You need to be careful that everything is properly insulated or you'll get a horrible "whine" in the sound system.

Posted by Anhtu Vu (Member # 7689) on 10-28-2019, 09:51 PM:

Will this VFD work ?

https://www.eaton.com/us/en-us/catalog/industrial-control--drives--automation---sensors/powerxl-dc1-variable-frequency-drives-na.html

and what motor would you recommend ?

Posted by Scott Norwood (Member # 30) on 10-28-2019, 10:26 PM:

I've always seen this done with AC motors and inverters, but DC motors are another option.

Or, if you don't actually need variable speed, you could replace the existing motors with fixed-speed AC motors.

There are some practical limits to the speed range that you can use. Simplexes require a minimum speed to keep the oil pump working properly, and slower speeds also cause more heat to be transferred to the film. You can definitely do 18-25fps on Simplexes, but slower or faster speeds may be problematic. especially with large lamps installed.

Posted by Gordon McLeod (Member # 33) on 10-29-2019, 10:15 AM:

We often used the Bodine 3 phase sync motors and a Baldor or Gavazi invertor drive

Posted by Anhtu Vu (Member # 7689) on 10-31-2019, 04:56 PM:

We use Superior Slo-Syn Motors and Slo-syn SS2000d6 . Unfortunately the latter just died and we're desperately looking to replace it.

We need 16 to 25 fps.

Posted by Jim Cassedy (Member # 4115) on 10-31-2019, 06:49 PM:

Boston Light & Sound used these GS-2 units on all their 35/70mm
installations for HATEFUL 8 & DUNKIRK, and I've also seen them at
several screening rooms I work at.
All the machines I've seen these installed on had Bodine 3-phase
motors, but I don't know the HP rating or which model number.

These work really well. What you see here is only the 'control head'
the actual electronics go inside the projector pedestal or console.

You'll have to do a little bit of math & programming to convert Hz to
FPS if you want it read out directly in Frames/sec as you see in my
photo, but I've had to do that with almost every VFD I've encountered.
As they say in North Korea: it's not rocket science

Posted by Anhtu Vu (Member # 7689) on 11-01-2019, 08:18 AM:

Hi Jim,

Thank you for the great info.

Do you have a contact at Boston Light and sound ? It would be great if i can get the exact model for all components.

Posted by Sean McKinnon (Member # 612) on 11-07-2019, 02:43 PM:

Anthu,

Feel free to email me at the address in my profile and I will help you out.