Induction Motors Specification

  • ID motors have cast iron stator frames, end shields and terminal boxes.
  • MS motors have aluminium stator frames, terminal boxes and cast iron end shields.
  • MS motors have bolt on feet, which can be located at 90 degree mounting locations, so that the terminal box can be on top or on either side.
  • IP55 as a minimum-higher ratings are available on request. Care must be taken when mounting motors in a nonstandard mounting position to maintain the IP rating of the motor.
  • Cooling to IC0141 up to 355 frames.
  • All motors are available in B3 (IMIOOI), B3/5 (IM2001), and VI (IM3031) confi guration. All standard motors up to 280 frame may be mounted in any direction, i.e. shaft up, shaft down, etc.They can also be mounted B5 (IM3001).
  • B14A and B14B fl anges are available up to 160-frame size.
  • Standard motors are rated for. continuous duty at full nameplate rating - S 1.
  • Standard voltage is 415v 50Hz.
  • Voltage tolerance is +/-l 0%. Voltages beyond these limits will cause a high winding temperature rise.
  • INVERTEK motors are designed for operation in high ambient temperatures of 40 deg C or more.The standard data relates to ambient up to 40 deg C. and altitudes below 1000 meters.
  • Standard motors have Class F (155 deg C.) insulation, with a Class B (80 deg C.) temperature rise. Class H insulation motors (180 deg C.) are available on request only high quality polyester covered copper winding wire is used in conjunction with inorganic high temperature polyester varnish.
  • Stator and rotor laminations are produced from low loss, double insulated, silicon electrical steel. All motors are designed for high effi ciency and low temperature rise giving a long economical service life.
  • In general INVERTEK motors have high starting torques and low starting currents because the rotors have a double cage design which is pressure die cast in high purity aluminium.
  • These motors have very low vibration levels due to high precision balancing of the rotors and fans. Most motors have vibration levels of less than 1 mm/sec.
  • High quality vacuum degassed SKF or NSK bearings are used on motors. In general the bearings have C3 clearances and are preloaded with a wave washer on the drive end which increases bearing life and reduces bearing noise. The nondrive end bearing is locked to prevent shaft "float.' Motors up to 132 frames have "'ZZ" sealed for life bearing, while motors from 160 frames and above have open bearing with "flush through" greasing facilities. In line with current practice, motors up to 280 frames have deep groove ball bearing at both ends, while the 315 and 355 frame motors have a roller bearing on the drive end. Roller bearings can be fi tted on the drive end of any motor on request.
  • Recommended grease for re-greasing is Shell Alvania R3.
  • Special bearing arrangements can be accommodated such as fitting angular contact,or 4-point contact QJ bearings,for thrust loads.
  • All bearings are protected from the external environment with oil seals on the drive and non-drive end.
  • Labyrinth seals can be fi tted as an option for external, protection of bearings for 160 frames and above.
  • Standard noise levels, (sound pressure at I meter), are well within the requirements of most standards, and are generally below 80 dB (A) for small motors and 85 dB (A) for large motors.
  • Shafts are made from high quality carbon steel.
  • Stator frames are made of T200 grade cast iron from 80 frame upwards 80 to 132 are also available in aluminium.
  • End shields for all motors are made from T200 cast iron.
  • Terminal boxes are made from aluminium for MDIA motors, and cast iron for ID 1 C motors. For 160 frame and above, all terminal boxes are cast iron. All terminal boxes are top mounted.
  • Cable gland entries are metric as standard and the thread sizes are specifi ed with the dimensional data in this brochure.
  • Fans are made from glass-reinforced polyproylene for small motors up to 280 frame size.The 315/355 frame motors have aluminium.
  • Fan Cowls are made from pressed steel for all motors up to 315 frame, and from cast iron for 355 frame.
  • Motors can be supplied with force ventilation systems for variable (VVVF) frequency applications.
  • Rain hoods are available for motors mounted shaft down.
  • RTD's or thermostats can be supplied as an option.
  • Anti-condensation heaters can be fi tted as an option to all motors and recommended for IP56 and IP66 motors.
  • All motors can be supplied with separate terminal boxes for heaters and/or thermistors.
  • All bolts and screws are zinc electroplated as protection against corrosion.
  • All cast iron motor parts are cleaned and primed (polyvinylbutyral and epoxy) to 25 microns or more before machining. Aluminium parts are painted with etch-primer on external surfaces.The final topcoat of paint is airdrying enamel. Based on epoxy polymer resins to 25 micron or more in thickness.
  • 80-180 frames are available in aluminium and cast iron 200-355 frames are only available in cast iron.

Duty Cycles

Continuous Duty
Operation under constant load, lasting long enough to allow the machine to reach thermal equilibrium.
Short-Time Duty
Operation under consant load, for a time too short to allow the machine to reach thermal equilibrium. Idle time of the machine is long enough to allow the machine to cool down to ambient tempsrature. Standard duration of short-term operation: 10, 30, 60 and 90 minutes.
Intermittent Periodic
Operation under repeated, constant load in specified cycles. Neither operating nor resting period are long enough to allow the motor to reach thermal equilibrium. The starting losses are small and do not essentially infl uence the temperature rise.The nominal values of relative starting time are 15, 25, 40, 60% at a daily 10-minute cycle.
Intermittent Periodic
Operation under repeated, constant load in specified cycles.The start of the motor influences the temperature rise.


The components of the insulation system are selected so as to ensure good protection against chemically aggressive gases, vapours, dust, oil and air humidity. All materials used for insulating the winding and winding ends correspond to insulating Classess F or H according to IEC 60085:

  • Enamel-insulated copper wires with temperature index 200 (Class H);
  • Insulating sheet on polyester base (Class F);
  • Impregnation with fenolic resins modifi ed with polyester resins (Class H);

Limited temperature for insulating material according to 1EC 60085

Insulation Class Limit Temperature (°C)
B 130
F 155
H 180

Temperature Rise

Standard single-speed continuous duty (Sl) motors have temperature rise within Class B limit. Motors with higher output and pole-changing motors normally have temperature rise within Class F limit.

Insulation Class Limit Temperature (°C)
B 80
F 105
H 125

Temperature rises specifi ed at a reference ambient air temperature of 400°C.