DC Motor
Specification
3-600 HP
Abstract
This specification covers DC motors designed specifically for static power supplies and
power matched to the controller.
1.0 Duty and Standards
Motor design will be rated for continuous duty at 1.00 service factor.
Short time ratings should be clearly identified and specifically designed. Motors will meet NEMA MG-1,
IEC 34. Motors should be CSA, and CE approved, and U/L component recognized.
2.0 Frame
The motor frame shall be constructed from insulated steel laminations with a minimum of 200 psi interlaminate pressure which presents an electrical barrier to the formation of eddy currents induced by the static power supply.
3.0 Enclosure
The motor shall have as a minimum a drip-proof guarded enclosure as defined by NEMA MG1-1.25.5 to prevent accidental exposure to live metal or rotating parts. The drip-proof construction permits successful operation when drops of liquid or solid particles strike or enter the enclosure at any angle not greater than 100 degrees downward from the vertical. If specified, the motor shall have a blower driven by a constant speed AC motor mounted on the end bracket to provide cooling independent of the DC motor.
When DPFV or DPSV are specified, no internal fan shall be acceptable. Design must be optimized for forced ventilation.
If specified, the following enclosures may be provided:
- DPSV Drip proof separate vent
- TEAO totally enclosed air over
- TEDC-AA Totally enclosed air to air heat exchanger
- TEFC Totally enclosed fan-cooled
- TENV Totally enclosed non ventilated
- TEDC-AW Totally enclosed air to water heat exchanger
4.0 Hazardous Locations
Motors for Division 1 locations shall be U/L listed and have a Totally Enclosed Non-Ventilated or Totally Enclosed Fan-cooled enclosure. Explosion proof motors have one or more thermostats designed to trip before the frame reaches the maximum allowable temperature for the specific class and group. The normally closed contacts of the thermostat must be connected in the motor control circuit so that power to the motor armature and field is removed immediately when the thermostat trips. Motors shall have a U/L listed conduit box and accessories.
Motors for Division 2 locations may be totally enclosed pipe-in, pipe-out enclosure provided the following guidelines are met:
- Available for Class I Group D applications only with temperature code T2D.
- Limited to rating 200 hp and smaller.
- Enclosure must be separately ventilated.
- Explosion proof conduit box must be provided.
- The thermostat leads must be connected in the control to automatically de-energize the motor if motor temperature increases beyond the design limits.
- Auxiliary equipment on the motor must be U/L listed for Class I Group D.
- An explosion proof air pressure switch is required for provide an immediate indication of cooling air loss.
5.0 Insulation and Temperature Rise
Insulation shall be rated not to exceed NEMA Class F temperature rise. Motors shall have insulation between the frame and the winding, Insulation shall include: Nomex ground insulation, polyester film coated high temperature magnet wire, resin saturated woven glass sleeving, glass tape on coils, high strength reinforced resin filled top wedges and coil retainers and high temperature varnish.
Temperature rise will be based on a ambient of 40× Celsius.
6.0 Field Windings
Motors shall have a stabilized shunt or straight shunt field. Interpoles will be integral to the frame lamination to insure consistent design.
Nomex insulation must be placed between field coils and frame. Entire frame assembly, with field coils and intercoils intact, shall receive multiple varnish dips and cures.
7.0 Armature
The armature shall be hand wound and connected. Skewed armatures are preferred.
Commutator’s shall be individually spin tested in the motor factory to ensure mechanical integrity.
8.0 Insulation
- Varnish shall be 100% solids epoxy. Each arm shall be given a minimum of two cycles of varnish and cure.
- Conductors shall be soldered to commutator
- Taping shall leave no exposed conductors on coil head or commutator end.
9.0 Brush Rigging Assembly
The brush rigging assembly shall have radial brush holders to insure constant brush pressure. The assembly shall provide 90× rotation on rocker for access to all brushes. The rocker will be match-marked at test to show the electrical neutral.
10.0 Sound Level
Motors shall be designed not to exceed 85 dba @ 3 ft sound pressure level with motor operating at base speed and full load on Power Code C (S-6) power supply.
11.0 Conduit Box
The conduit box shall be a heavy gauge steel type which can be located in any quadrant of the motor as long as no accessories are mounted in that same quadrant.
12.0 Bearings
Motors shall have open type anti-friction or roller bearings with a L10 life of minimum 100.000 hrs for coupled service.
13.0 Tests
Each motor will be given a routine test to determine that it is free from electrical or mechanical defects and to provide assurance that it meets design specifications. Tests consists of:
- Neutral check
- Winding resistance
- Commutation check
- High potential test
- No load test at base speed and maximum field weakened speed
- Full load test at base speed and maximum field weakened speed
14.0 Accessories
Motors shall have provision for addition of a flange mounted tachometer.
Motor shall be equipped with a high limit thermostat on the intercoil with leads brought out in the standard conduit box. One (1) thermostat, normally closed contact for use in control circuits rated 120-500 volts AC.
In addition, when specified the motor shall be equipped with a warning thermostat on the intercoil. The warning thermostat will selected to trip at 15× C below the high limit thermostat. |