mo-ta モーター

March 3, 2009

Oriental Motor Gearhead Grease

Filed under: AC Gearmotors — mota @ 7:19 pm

Q. What type of grease is used in Oriental Motor GN/GU Type gearheads?


  1. Parallel gearheads: Molybdenum grease
  2. Right angle gearheads: Molybdenum grease (parallel shaft section); Urea grease (hollow shaft section)

May 11, 2007

Finding a gearhead ratio without a part number.

Filed under: AC Gearmotors — mota @ 10:44 pm

First, separate the gearbox from the motor.

On the first stage of teeth, make a notch on one of the teeth. Not a big one or it’ll make noise when it’s put back together. Then turn the shaft of the motor until the notch makes a full revolution. The number of times that you have to turn the shaft is your gear ratio.

Then measure the diameter of the output shaft so I can tell if the gearhead it’s metric or inch standard.

mota tech support

November 28, 2006

Using an SB50 Brake Pack with Synchronous Motors.

Filed under: AC Gearmotors — mota @ 5:01 pm

There is a difference of winding between ACmotors and Synchronous Motors.

Motor                 resistance              resistance
of main winding       of auxikiary winding
3IK15GN-A           53.5Ω                  77Ω
3IK15GN-AW      59.6Ω               58.8Ω
3IK15GN-AUL      70.3Ω               71Ω
3SK10GN-A         57.6Ω              306.8Ω
3SK10GN-AUL      71.2Ω               234.8Ω

This winding difference makes higher voltage between the terminal of capacitor.
So the rated voltage of synchronous motor’s capacitor is 400WV and ACmotor is 250WV.
And this makes it possible to damage SB50.This is the reason why we don’t recommend
synchronous motor+brakepack.

If the customer must use brake pack with synchronous motor, please recommend SB31-IN with
following connection. This connection is the only way to protect the brackpack with using synchronous motor.

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October 7, 2006

Why do some of the OM motors have Class E (248F) insulation class windings, but UL only recognizes them as Class A (221F)?

Filed under: AC Gearmotors — mota @ 2:51 am

Class A (221F), Class E (248F), Class B (266F).

UL does not have a category for Class E, so we have to be recognized using the next lower class.

Replacing 220/240 VAC motors.

Filed under: AC Gearmotors — mota @ 2:49 am

These p/n’s are older K Series motors designed for the European market. When these were designed for 220/240, the stator targeted around 230V (middle of 220 and 240). Movex show these are “D” ranked, so now obsolete.

With the -CW motor, the stator design targets around 215V (middle of 200 and 230). This is a different design that one targeted for 230 (middle of 220 and 240). Today, OM only supplies World K type motors to Europe, as there have not been any “new designs” of 220/240 motors. Therefore the customer has these options:
1. Order a special motor for 240VAC or,
2. Use a transformer and a -CW motor or,
3. Use the -CW and test for temperature rise.

2 other important points:
1. Make sure the capacitor’s voltage is rated at about 2x that of the applied voltage. (e.g., 220VAC needs 450V cap., and 250VAC needs 500V cap.)
2. At high voltages, there will be much more torque (torque is proportional to the square of the voltage), so the gearhead will receive more shock during accel. and decel.

What is the service factor of OM’s AC motors?

Filed under: AC Gearmotors — mota @ 2:45 am

Service factor (a NEMA term) represents how much over the “nameplate rating” an AC motor can by driven without overheating. The OM catalog states rated torque which represents 100% of the load that should be applied to the motor, at the specified ambient temperature range. We don’t recommend any value over the rated torque, and have not tested for loads which will result in overheating. Therefore, our service factor is unity, or 1.0.

If the overloading is a result of the acceleration. and deceleration of the load to the motor, then the sizing of the motor needs to be considered. The starting torque would have to be greater than the total of acceleration torque and constant torque, multiplied by some safety factor.

Reversible motor duty cycle.

Filed under: AC Gearmotors — mota @ 2:40 am

Reversible motors have a higher starting torque compared to normal Induction motors to help it reverse directions quickly. This, in addition to the heat caused by the brake mechanism of the Reversible motor, makes the motor very hot and hence a 30 min. “ON” time (regardless of direction) rating. The key factors are the ambient temperature and duty cycle %. As long as the motor case temp. is below 90°C, you can safely increase the duty cycle % and/or the 30 minute rating.

Induction vs. Reversible motors.

Filed under: AC Gearmotors — mota @ 2:26 am

World K Series Induction and Reversible motors have the same stator design with balanced windings (primary and secondary coils wound the same), and the same rotor. The only difference is the capacitor. The higher capacitance value for the Reversible generates a higher starting torque for reversing, and eliminates the negative torque area in the speed-torque curve. The higher capacitance results in higher temperatures, which is why we have a limited duty cycle.

K Series Induction motors have 4 wires, and the Reversible has 3 wires. In the Induction motor, the primary is wound differently than the secondary, and is a more efficient motor. The Reversible motor has balanced windings. Sometimes, the rotor on the reversible will incorporate a lower head height, which increases the resistance in that area, resulting in a higher starting torque.

How far away can I wire the capacitor from the motor?

Filed under: AC Gearmotors — mota @ 2:20 am

There is not a published maximum distance. However, anything within 1m or so should be fine. Much farther than that, and we get away from the designed 90 degree electrical phase shift that the capacitor was sized for, since the wire itself has inductance and capacitance. As a result, the AC motor runs less efficiently, and therefore hotter.

Long wire runs also results in voltage drops. That would mean that the capacitor phase would have less torque (proportional to the square, or up to 2.5 power, of the voltage drop).

October 4, 2006

Should I use a zero-crossing type solid state relay (SSR), or a random phase type to operate the motor?

Filed under: AC Gearmotors, Speed Control Motors — mota @ 3:44 am

Zero-crossing type SSR’s cost more and lasts longer, but is safer in that it reduces sparks since it waits for the AC voltage to become zero before turning on. However, since current is delayed (due to coil inductance), there is still a small chance of sparking. Drawbacks: Delay in starting (waiting for zero crossing) and delay in stopping (due to residual current). ES controllers have a zero-crossing SSR built into them.

When designing a circuit with SSR’s, which reverses a reversible motor on-the-fly, make sure that there is at least a 30ms delay between the CW turning off and CCW turning on. This is because the residual current makes the motor continue CW, while the CCW command will make the motor try to start in the CCW direction. Without a 30ms delay, this could cause a problem in operation. The ES Series already has this 30ms delay built in.

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