MV Switchgear Installation Method Statement

This method statement for installation of medium and low voltage switchgear and panels boards on site is prepared to define the method used to ensure that all MV/LV switchgear and panels site assembly, installation, final connection and workmanship is correct and acceptable and conforms to the contract documents & electrical specifications.

The Project Manager is the overall responsible person for the process of implementation of the works.

Construction Manager/Site Engineer will be responsible for all construction activities at the site and will directly supervise through erection supervisor/skilled workmen at  the work  site.

Site Engineer will be responsible for arranging and controlling the inspection and testing activities.

Construction Manager, electrical engineer and Quality engineer are responsible for site implementation of below method statement.

Equipment to be Used

• PPE for all staff and labor
• Measuring tape and setting out markers
• Drill Machine
• Mobile Crane
• Chain Block
• Hand Tools
• Electricians tool box

Pre Installation Checks

Prior to the commencement of mv switchgear installation works, access and installation areas will be inspected to confirm these are in suitable condition to commence installation.

Housekeeping pads or pertinent structure are complete and leveled within (±5) by civil contractor, for all plinth sizes.

Site supervisor shall carry out pre installation inspection of plinth prior to off loading and positioning the electrical panels in accordance with manufacturer instructions and detail drawings.

Construction department will ensure temporary protection is provided to protect the openings during installation and until the final connections are made to the Motor Control Centre.

Check equipment schedule for correct location and reference for the switchgear and panels.

If the switchgear or panels cannot be installed immediately, then the same shall be stored in clean, dry and properly ventilated location.

Switchgear & Panels Installation Procedure

Fully crated switchgear panels shipped on a timber sub-base will only be lifted from under the sub-base, in between the bearers, using soft sling’s (Nylon webbing) with spreader bars on the topside of the crate.

When transferring using the fork lift, or unloading with a fork lift, the mast must be as close as possible to the face of the crate.

Forks must be fully projected under the crate.

Lift switchgear or mv panels squarely, then tilt back towards the fork lift before moving.

When the switchgear panels has been moved to the final installation location, it will be un-crated, unpacked and removed from its timber base.

Where needed lower switchgear panels onto lengths of steel conduit or skate (rolling devices), for movement to final location.

Care will be taken to ensure the mv switchgear / panels do not unbalance whilst being moved to its final location.

Once in its final location on the “Housekeeping Pad”, rolling device’s will be removed from under the switchgear or panels.

Again caution will be exercised against over balancing, while the panels are being moved.

Finally the panels should be free standing, self supporting assembly, and will be bolted to the “Housekeeping Pad” with anchor bolts ensuring the assembly is horizontal and vertically in alignment as detailed on the construction shop drawings.

Assembling the LV / MV Switchgear Panels At Site

When the switchgear panels are shipped in more than one module, these individual section will be assembled / bolted together in the presence of manufacturer/supplier representative.

Construction drawings will indicate the relative positions of each section being supplied and shipped.

All fishplates to interconnect bus bars will be carefully installed after removing the appropriate cover plates.

Connection bolts will be tightened to the required torque value as per data from the manufacturer.

Busbar Assembly Torque Data:

Torque setting for fault level Bus-Bars using ISO M8.8 graded cadmium plated bolts or set screws.

M6 Bolt or set screw: 7 lbs. ft. 8.6 Nm

M8 Bolt or set screw: 15 lbs. ft. 20.4 Nm

M10 Bolt or set screw: 23 lbs. ft. 33.6 Nm

M12 Bolt or set screw: 40 lbs. ft. 54.0 Nm

M8 set screw into Brass: 15 lbs. ft. 20.4 Nm

Termination Of Incoming Cables

The switchgear panels are provided with terminals for both power and control cables.

Terminals will be positioned in such manner as to facilitate optimum access to suit the specified type of entry, as detailed on the construction/shop drawing.

Operate all components (i.e.. fuse switches, circuit breakers, contactors, relays etc.) by hand to ensure that there is no damage to the moving parts.

A thorough inspection will be carried out to determine that no foreign matter (tools etc.) have been left in the panels after field installation is complete.

Particular attention will be given to the Busbar compartment, ensuring it is free of debris and moisture, all compartments shall be thoroughly cleaned.

All busbar and circuit connections shall be checked carefully to find these are tightened and torqued from the factory, as it is possible for connections to vibrate loose during shipments.

Also all connections are checked for tightness/torque prior to energization in accordance with the manufacturer’s recommendation.

All components/door interlocks should be adjusted correctly and must operate freely.

After the above operations, all doors are closed and locked and keys should be maintained by the supervisor until panel is ready to handover to the commissioning team.

The supervisor in charge and the QC officer will continuously monitor the activities to ensure that all components on the approved construction drawings and coordinated service drawings have been installed and that the panels installation is completed in accordance with the contract requirements and manufacturer’s recommendations.

Frame and mount  the printed basic operating instructions for  panels/ distribution boards,  including  control and  key  interlocking sequences and  emergency  procedures.

Fabricate frame of finished wood or metal and cover instructions with clear acrylic plastic. Mount  on front of panels/ main distribution boards.

Battery Charger Installation

Determine the preferred layout and ensure the socket-outlet is located near the equipment and easily accessible.

Ensure the unit is plumb then mark through the four screw holes to identify where the pilot holes will be drilled.

Using a 1/16-inch bit, drill pilot holes at the marked locations.

Mount the unit using the pan head screws.

Route and connect all cabling to the appropriate device.

Use cable tie down as needed.

Connect the ground stud using the most direct route to known equipment ground source.

Battery Rack Installation

Consider available space including aisles for cell installation, maintenance and possible cell replacement.

Locate racks to minimize temperature variation between cells.

Do not locate the battery near HVAC ducts of exhaust, heat sources (i.e. equipment that generates heat or direct sunlight).

Adequate ventilation must be provided.

Do not Install in an air tight enclosure or room with no ventilation.

Mark location for anchor bolts using the holes in the bottom of each frame as template.

Install floor anchors in pre-determined locations.

Align rack with floor anchors and attach to floor.

Shimming up to 0.25 in.(6mm) maximum may be required to level support rails both front-to·back and side-by-side.

Recheck all bolted connections for proper  torque as directed in manufacturer’s instruction.

Place frames at the floor locations.

Attach cross braces to frames for strength and rigidity between the frames.

Bolt cross braces together where they cross each other.

Make sure frames are plumb before tightening bolts to the required torque.

Attach the support rail to assembled frame.

Place rail on frame clamp nut push bolt assembly upward.

Rotate clamp 90″ fasten bolt.

Position each rail so the overhang beyond the frame is equal to each end of the rack or as specified on the rack assembly drawing.

With the frame, braces and rails assembled, check frame alignment and tighten all bolts as indicated.

Attach corner brackets to end rails to prevent batteries from falling from rack during a seismic event.

Ground rack according to local codes.

Periodically check using the ohmmeter to determine that all components of the rack are still grounded.

If the ground becomes lost on any component, loosen one bolt at a time and tighten to the original torque value.

Continue to do so until continuity has been reestablished.

Periodic inspections of the entire battery rack are to be made to observe any signs of acid corrosion.

When corrosion is detected, scrape away the corrosion to bare metal.

Neutralize the area with the solution of bicarbonate soda and water (1pound of soda to 1 gallon of water), dry, and then paint the area with acid-resistant paint.

All the necessary records shall be maintained as per approved standard formats.