- Always disconnect power to the motor if voltage is higher than 48v before performing any service or maintenance.
- Keep hands and clothing away from moving parts.
- Ensure that all required safety guards are in place before starting equipment.
What to do
Problem 1: On initial installation, motor fails to start up.
Motor is incorrectly wired.
Verify that the motor is wired correctly.
No output power from controller.
Measure voltage coming from the controller.
Motor is damaged and the armature is rubbing against the magnets.
Disassemble motor and see if the armature can be realigned by reassembly. Motor may have to be replaced.
Problem 2: Motor has been running then fails to start.
Fuse or circuit breaker is tripped.
Replace the fuse or reset the breaker.
Armature is shorted. Motor may make a humming noise and the circuit breaker or fuse will trip.
Disassemble motor and inspect the armature for a burnt coil. Inspect the commutator for burnt bars. If this condition exists, the motor needs to be replaced.
The brushes may be worn down too far and no longer make contact with the commutator.
Check the brushes to make sure that they are still making contact with the commutator. Contact manufacturer for brushes.
Controller may be defective.
Verify voltage is coming out of the controller.
Problem 3: Motor runs but loses power.
Load had increased.
Ensure that the load has not changed. Measure the amp draw of the motor against the full load amp rating of the motor. If the amp draw is higher than the rated one, the motor is undersized for the application.
Motor controller not properly set.
Check controller manual for adjustments. The torque and/or IR compensation settings may need adjustment.
Motor may have an open connection.
Inspect the armature for an open connection.
Brushes may not be seated properly or worn beyond the useful length.
Verify that the brushes are properly seated and measure their length.
Problem 4: Motor takes too long to accelerate.
Motor controller not properly set.
Adjust the acceleration trim pot of the controller.
Brushes are worn.
Verify brush length.
Bearings may be defective.
Inspect bearings. Noisy or rough bearings should be replaced.
Problem 5: Motor runs in the wrong direction.
Interchange the two motor leads.
Problem 6: Motor runs OK but has a clicking noise.
Suspect a burr on the commutator.
Remove burr from commutator using a commutator stone.
Alternative Current (AC)
The standard power supply available from electric utilities.
The standard unit of electric current. The current produced by a pressure of 1v in a circuit having a resistance of 1ohm
The rotating part of a brush-type direct current motor.
Used in industrial & agricultural motors.
The maximum torque a motor can achieve with rated voltage applied at rated frequency, without a drop in speed or stalling.
Current conducting material in a DC motor, usually graphite or a combination of graphite and other materials. The brush rides on the commutator and forms an electrical connection between the armature and the power source.
A basic measurement for worm gear reducers, measured from the centreline of the worm to the centreline of the worm wheel.
Non-uniform or erratic rotation of a direct current motor.
The part of the DC motor armature that causes the electrical current to be switched to various armature windings.
The power supply available from batteries, generators or rectified sources used for special purpose applications.
The relationship between the operating time and the resting time of an electric motor. Motor ratings according to duty are:
Ø Continuous Duty: the operation of loads for over 1 hour.
Ø Intermittent Duty: the operation during alternate periods of load and rest. It is usually expressed as 5 mins, 30 mins or 1 hour.
A ratio of the input power compared to the output, usually expressed as a %.
Used to describe the motor housing.
The part of the motor that houses the bearing supporting the rotor and acts as protective guard to the internal parts of the motor.
The stationary part of a DC motor, consisting of permanent magnets.
Standardized motor mounting and shaft dimensions as established by NEMA or IEC.
Full Load Amperes
Line current drawn by a motor when operating at rated load and voltage.
Full Load Torque
The torque the motor produces at its rated horsepower and full-load speed.
A piece of metal, connected in the circuit to be protected, that melts and interrupts the circuit when excess current flows.
Any machine that converts mechanical energy into electrical energy.
A measure of the rate of work.
In motors, classified by maximum allowable operating temperature. NEMA classifications include:
Class A=105˚C, Class B=130˚C, Class F=155˚C and Class H=180˚C.
A unit of power equal to 1000 watts and appx. Equal to 1.34 horsepower.
The work required of a motor to drive attached equipment. Expressed in horsepower or torque at a certain motor speed.
A break in an electrical circuit that prevents normal current flow.
The amount of horsepower available at the output shaft of the reducer (gear box). Output horsepower is always less than the input horsepower due to the efficiency of the reducer.
The shaft of a gear box assembly that is connected to the load.
A device that resists the flow of electrical current for the purpose of operation, protection or control.
The direction in which a shaft turns is either clockwise (CW) or counter clockwise (CCW). When specifying rotation, also state if viewed from the shaft or opposite shaft end of motor.
A fault or defect in a winding causing part of the normal electrical circuit to be bypassed, frequently resulting in overheating of the winding and burnout.
In adjustable speed drive systems, speed regulation measures the motor and control’s ability to maintain a constant preset speed despite changes in load from zero to 100%.
The fixed part of the AC motor, consisting of copper windings within steel laminations.
TENV (Totally Enclosed Non-Ventilated)
No vent openings, tightly enclosed to prevent the free exchange of air, but not airtight. Has no external cooling fan and relies on convection for cooling. Suitable for use where exposed to dirt or dampness, but not for hazardous (explosive) locations.
TEFC (Totally Enclosed Fan Cooled)
Same as the TENV except has external fan as an integral part of the motor to provide cooling by blowing air around the outside frame of the motor.
The turning effort or force applied to a shaft.
Ø Starting Torque: Force produced by a motor as it begins to turn from standstill and accelerate.
Ø Full-Load Torque: The force produced by a motor running at rated full-load speed at rated horsepower.
A unit of electromotive force that, when applied to conductors, will produce current in the conductors.
The amount of power required to maintain a current of 1A at a pressure of 1v when the two are in phase with each other. One horsepower id equal to 746 watts.
Refers to the process of wrapping coils of copper wire around a core, usually of steel. In a permanent magnet DC motor, the winding is the rotating armature.
TECHNICAL REFERENCE GUIDE:
Electric motors are devices using electrical energy to produce mechanical energy and can be found everywhere; in your house or your work. They are used in countless applications and can be operated by direct current or from alternating current. Direct current (DC) motors are used in applications where exact speed control is required or when battery or generated direct current is the available power source.
We recommend that you take the time to record the information provided on the EMP data label as it can save time and avoid confusion when looking for a replacement motor. Looking for the right motor for a new application is also easily done if the following information is known:
Ø EMP Data Label
Ø Motor Type
Ø Frame NEMA standard (D56, D63, D71, D80)
Ø Mechanical Construction
Ø Electrical & Performance Characteristics.
An EMP Data Label will display the following information:
Model Number: Mx-xxxxxxx
HP (watts) Horsepower rated at full load speed
RPM Revolutions per minute of the shaft at full load
Amperage Full load motor current
Duty Continuous or intermittent
Gear Box Selection:
When selecting a gear box/reducer for your application, the speed at the gear output relates to the motor speed with the following formulae:
Nq = Nm / Ratio
Tq = Tm x Ratio x η%
Where: η = Efficiency of the Gear Box
Tm = Motor Torque
Tq = Gear box torque
Nm = Motor speed
Nq = Gear speed