Electrical Works Specifications i
Issue 01 / Revision 01
Page
Section 5 – Motor Specification
1.0
Submersible Motor
5-1
2.0
Surface Mounted Motors
5-2
2.1
General
5-2
2.2
Indoor Type Motor
5-3
Section 5 - Motor Specification
Electrical Works Specifications Sec 5 - 1
Issue 01 / Revision 01 February 2007
SECTION 5 – MOTOR SPECIFICATION
1.0 SUBMERSIBLE MOTOR
The electric motor shall be a 3 phase, squirrel-cage induction type running at not more than 1,500 rpm suitable for 50 cycles, 415 V and complying with BS 5000 or BS 4999. The motor shall be built for submersible operation, Class IP68 according to IEC. The motor shall be able to withstand a minimum depth of 20 m submergence.
The motor stator shall be shrunk fit into an air-filled watertight stator casing. Externally mounted screws that may cause leakage into the motor shall not be used. The motor casing and sealing arrangements shall be designed waterproof to Class IP68.
Motor bearing and shaft shall all the loads induced by the short-coupled i.e. pump impeller and mixer propeller.
The motor shall be capable of operating continuously with full load without overloading throughout the operation. It shall be able to tolerate voltage variations of up to ±10% of the rated voltage of 415 V without overheating. The motor shall operate at voltage imbalance of up to 2% between phases and current imbalance of up to 4% between phases.
The motor shall start by direct on-line, star-delta, auto transformer, soft starter and variable speed drive in accordance with the size of the motors.
The motor shall run continuously or intermittently with a maximum of 15 evenly spaced starts per hour. The motor shall be tested in accordance to IEC 34-1.
The stator shall be moisture-resistant and triple-varnished and shall be insulated to Class F (IEC publication) capable of withstanding temperatures up to 155oC (to confirm the spec.), however the maximum temperature rise shall not exceed 80oC.
The motor shall have a terminal box capable of sealing off the junction box completely from the stator casing to prevent leakage through the junction box into the stator housing. The cable entry water-seal design shall be such that the cables are sealed off by a compressible rubber bush and fitted with cable strain relief clamps. The design shall preclude specific torque requirements to ensure a water tight and submersible seal. Epoxies, silicon resin or other secondary sealing systems shall be used.
The stator shall incorporate three thermal switches connected in series for monitoring purposes. Thermal sensors shall protect the stator from overheating in the case of asymmetric phase loading or voltage, continuous dry run or excessive temperatures in the medium itself. For motor rating of 37 kW and below, a minimum motor protection shall incorporate a leakage sensor at the seal chamber and a PT 100 or better in the stator winding. For motor rating of 37 kW and above, a full monitor motor protection shall be incorporated. The leakage sensor shall be located at the upper terminal area, lower motor area and seal chamber. The thermal sensor shall be located at the upper and lower bearing housing and stator winding.
Power to the motor is supplied by one or several flexible cable(s) that connect to the motor through a sealed inlet to a connection box. The cable is supplied to specified length by the manufacturer.
Section 5 - Motor Specification
Electrical Works Specifications Sec 5 - 2
Issue 01 / Revision 01
The cables contain a sufficient number of leads for motor start and operation as well as for control impulse transmission.
The motor is dimensioned for cooling submergence in the pumped liquid. For dry installation, cooling is provided by liquid circulating in a cooling jacket or by other means of heat transfer into the pumped liquid.
2.0 SURFACE MOUNTED MOTORS
2.1
General
Electric motors shall be manufactured and shop tested to BS 4999 and BS 5000. Motors shall be tropicalised 3 phase squirrel cage induction type. Both indoor and outdoor surface mounted motors shall comply with IEC 34-1 Electrical and IEC 72-1 Mechanical Specification. The motor shall be tested in accordance to IEC 34-1. 3-phase cage rotors shall be robust in design and construction and capable of running continuously for prolonged periods with minimum attention.
Motor bearing and shaft shall carry all the loads induced by the short-coupled i.e. pump impeller and mixer propeller.
The motor shall be manufactured in a one-piece stator frame casing. The feet shall be integrally cast into the stator frame. For most frames the terminal box shall be mounted on the top as standard. The terminal box can be rotated so that cables can be connected from the right and left.
All shaft diameters shall be machined to IEC 60072 for ease of fitting, removing or securing fitments, a tapped hole in the drive end shaft.
Tolerances on main performances parameter shall comply with IEC 60034-1 specifies allowable tolerances for efficiency, power factor, speed, locked rotor torque, pullout torque, starting current and moment of inertia.
Ball bearings shall be used for motors having aluminium frames. Motors with cast iron or fabricated steel frames shall have ball or roller bearings. Ball bearings shall be grease lubricated. Working thrust loads shall not be placed on the motor bearing.
The motor fan shall be made of light aluminum alloy.
The motor shall start by direct on-line, star-delta, auto transformer, soft starter and variable speed drive in accordance with the size of the motors. Motors shall be equipped with their own starters and shall run at not more than 1,500 rpm, unless specified otherwise. Motor starters shall be fitted with a no-volt release and thermal overload in each phase. Motors and their associated starters shall be suitable for operation on a 415 V, 3-phase and 50 Hz supply.
Motors shall be capable of continuously running and shall be able to tolerate voltage variations of up to ± 10% without overheating in accordance with BS 5000 S1 designation. The motor shall operate at voltage imbalance of up to 2% between phases and current imbalance of up to 4% between phases.
Section 5 - Motor Specification
Electrical Works Specifications Sec 5 - 3
Issue 01 / Revision 01 February 2007
PT 100 or better shall be built into the motor windings for motors above 3.75 kW. It shall act either to give an alarm or to stop the motor.
The stator shall be moisture-resistant and triple-varnished and shall be insulated to Class F (IEC publication) capable of withstanding temperatures up to 155oC, however the maximum temperature rise shall not exceed 80oC, Class B.
2.2
Indoor Type Motor
The types of motor enclosures and degree of protection for electric motors to be used in different areas shall be as follows: -
Totally Enclosed Fan Cooled Type (TEFC) to be used in damp and dusty indoor areas and shall have a service factor of not less than 1.15 or greater.
2.3
Outdoor Type Motor
The types of motor enclosures and degree of protection for electric motors to be used in different areas shall be as follows: -
Motors shall be with Class F insulation and IP55 enclosure. Motors shall be single speed Totally Enclosed Fan Cooled (TEFC) and rated for continuous use. It shall have a service factor of not less than 1.15 or greater.
Section 6 - Low Voltage Cable Specification & Installation
Electrical Works Specifications Issue 01 / Revision 01