This article is about installation of electric motor in plants, refineries and commercial buildings. I am going to discuss about steps involved in installation of motor, preparation required, standard codes used, and how to inspect and test motor.
Preparation for Installation of Motor.
- All permanent materials (including fabricated and pre-fabricated supports), consumables, construction area and resources shall be prepared and checked prior to installation works.
- Ensure that all Electrical Equipment and materials, which would suffer damage or deterioration from exposure to the elements has been properly stored indoor, off the ground in suitable warehousing.
- Special tools shall bear a valid calibration certificates traceable to a national standard indicating calibration validity and periodically (maximum of six months) checked by a third party laboratory testing facility.
- Electrical materials shall conform to all applicable requirements, standard, and specifications prior to release to be used as part of the work.
Motor Installation Procedure.
Step by step procedure for installation of motor is summarized below in points.
- Review all references such as the latest approved for construction drawings, layout, and Technical Scope of Work.
- Ensure the manpower, equipment and other resources are prepared prior to start of the activities.
- Vendor’s installation instructions shall always be reviewed together with the plans from time to time during the course of the installation activities.
- Check the readiness of concrete foundations: anchor bolt, embedded steel bars, etc. The result shall be reported to company, and a turn over report for concrete foundations shall be provided by Civil Sub contractor, before motor installation takes place.
- Check the installed wireways and its access to suit the electrical equipment and devices for the installation ensuring a neat and proper installation as per Technical Scope of work and standards.
- The junction box shall be permitted to be separated from the motor by not more than 1.8 m (6ft), provided the leads to the motor are Type AC cable or armored cord or stranded leads enclosed in liquid tight flexible metal conduit. According to NEC 430.245(B).
- Sufficient access and working space shall be provided and maintained about enclosure housing electrical to permit ready and safe operation and maintenance of such equipment, NEC Art. 110.26.
- Mount the equipment in the position and location as shown on Equipment Location Plan, pertinent Approved for Construction Drawing.
- Equipment shall be placed and leveled in proper position.
- All threads and plugs, junction boxes and other fittings shall be lightly lubricated with rust preventive grease before assembly. All unused entries to electrical devices shall be plugged to prevent ingress of sand or other foreign matter.
- Provide a proper grounding bonding to all equipment and/or devices as approved and shall be connected to grounding bus bar that is to be continuously connected to grounding grid.
- All equipment shall be identified by means of stainless steel nameplate affix with stainless screws.
- Visual inspection shall include dimensional check and verification of exact location shall be conducted with respect to the latest issued Approved for Construction Drawings that will be recorded using appropriate inspection form.
- QC inspection for the completed panels, junction boxes and peripherals installed and its steel supports and stanchion shall be requested while the inspection results shall be filed and recorded using appropriate inspection form during walk through.
- Do Pre-Energization walk through.
Inspection and Testing Required after Installation of Motor.
Following we summarized the list of inspection points and testing required after installation of induction motor.
- Check documentation for the material receiving of motor for any comments.
- Terminals of motors and controllers shall be suitably marked or colored where necessary to indicate the proper connection.
- Motor shall be located so that adequate ventilation is provided and so that maintenance, such as lubrication of bearings and replacing of brushes, can be readily accomplished.
- Open motors that have commutators or collector ring shall be located or protected so that sparks cannot reach combustible material.
- The arrangement of the equipment, including number of bearings, terminal housing, conduit, piping, and auxiliaries (including the rotating element of the exciter, the field discharge resistor, and synchronizing controls as applicable) shall be provided with adequate clearance areas and safe access for installation, operation and maintenance.
- The motor and all of its auxiliary devices shall be suitable for and in accordance with the area classification system specified based on the data sheets.
- The frames and other metal exteriors of motors (except for insulated pedestal bearings) should be grounded to limit their potential to ground in the event of accidental connection or contact between live electrical parts and the metal exteriors.
- The connection of the motor to the power supply should be made by qualified personnel in accordance with the diagram or other instructions furnished by the motor manufacturer.
- Inspect physical and mechanical condition of motor.
- Check the screens, guards and other personnel protective devices are in place.
- Check the motor is properly installed and aligned to the load and its coupler is disconnected.
- Check proper rotation of motor. (Use proper precaution for vertical motors).
- Measure and record the heater and RTD resistance.
- Perform megger test or insulation-resistance test for the motor winding.