Friday, December 4, 2009

INSTALLATION,OPERATION AND MAINTENANCE OF LOW VOLTAGE DISTRIBUTION BOARD

STORAGE

In the event of delay in installation, the panels should be stored in a covered space.

INSTALLATION

The Panels after reaching the site i.e. place of installation, the following procedure should be followed for installation: -

1.Ensure location of installation should be adequately ventilated and free from dipping water, water logging, sources of heat etc...

2.Remove the wooden packing case (if packed in wooded case) by removing top of cover first and then four sides. Due care should be take so that the packing case opening tools do not hit any of the instruments provided on the front of the panel. Remove the panel from wooden base frame.


3.Remove polythene and paper covering sheet from the panel. Remove corrugated paper packing (in case of paper packing only) from the panel.


4.Check the material as per the packing list provided for this purpose.



5. Ensure proper protection from mechanical damage which may be caused by activities in the surroundings is provided.

6.Components projecting out from the Panel Boards viz. metering glasses, instrument windows, rotary handles, switches, relays etc. shall be protected during installation activities.


7.Align various shipping sections of the panel (In case of panels with multi transport section) in one line on the place of installation. Check the straightness of panel. Check the vertical placement of panel with the help of plumb line and if required use thin packing to adjust vertical plumb of panel.


8.Tighten various panels with each other with the help of nuts and bolts provided for the purpose on one side of each transport section and ensure that rubber gasket is available between two transport sections which are also provided on one side of each transport section.


9.Join bus bar of various transport sections with bus bar jointing fishplates and nuts and bolts provided for the purpose. The required fish plates are fixed on one side of main horizontal bus bars of each transport section duly reversed and tightened with nuts and bolts. On the other side of horizontal bus bars required number and sizes of nuts and bolts are provided.


10.Fix panels with the base channel provided on the trench with the help of foundation bolts or by welding. The panels with top cable entry i.e., without trench can be fixed by grouting panel to pockets provided in the floor for this purpose with the help of foundation bolts.


11.Check all the bus bars jointing and supporting bolts for any looseness as they might have loosened in transport. If so found the same should be tightened properly preferably with a torque wrench.


12.Check for looseness of any wiring on auxiliary control equipment and tighten them properly as the same might have also loosened in transport.


13.Carry out power and control cabling for both incoming and outgoing feeders. Also connect control wires in the terminals for inter-panel wiring provided for this purposes on both sides of transport sections. (In case of electrical interlocking of 2 or more I/C feeders).


14.Un drilled gland plates are provided at the bottom to facilitate cable entries. Ensure to plug extra / vacant entries after completion of work to arrest entry of rodents, vermins and dust.

15.Restore insulated shrouding if removed while cabling is being done

16.Check for any foreign material or tools left over in the panel at the time of installation and cabling.



17.Clean the panel with the help of vacuum cleaner.


18.Station earthing should be properly connected to the earth studs / earth bar provided on both sides of Panel.


19.Current Transformers are provided with shorting links. Ensure links are open before commissioning of the Panel Board. In case a device is connected to CTs needs to be disconnected or not supplied, close the links to those CTs ensuring safe grounding.

20.Carry out Megger test (insulation) for the panel, check for satisfactory results.


21.After all above points are completed satisfactory, the Panel Board is ready for energisation.




OPERATION

1)The Panels should be put in to operation only after completing erection of pre-commissioning checks including the safety precautions i.e. all insulating guards/shrouds to be in position.


2)First, the incomer circuit breaker shall be made ON by pressing Knob of the ACB (or) by operating the handle of MCCB/ISOLATOR, to ON position and check the voltage between phases and neutral.

3)Switch ON the outgoing feeders step by step so as to feed the connected load.


4)Check the load condition on each outgoing feeder by means of a tong meter . The reading should be less than the rating of the MCCB.


5)Check total load on the panel by measuring the current in incoming feeder to ensure that connected load is not exceeded.


6)During exigencies, if any, switch off the incomer feeder.


7)Once the switching devices have been operated as required, ensure that all doors, covers etc. are properly closed.







MAINTENANCE


The Panels should be maintained periodically. A reference chart for maintenance is attached for reference. However, if required, frequency may be increased by concerned engineer depending on place of installation, and frequency of operation of panel & the electrical components mounted therein. Maintenance works inside the Panel shall be done only after taking proper power shutdown.

A. Precautions before starting maintenance:


1. Switch off incoming power supply before removing outer covers.

2. Measure voltage on busbars to ensure that busbars are de-energized.

3. Switch off the control supply.

4. Isolate remote control voltage sources, if any.

5. Ensure that only qualified personnel are instructed and permitted to attend the maintenance.

6. Do not attempt to disconnect any terminations when the door interlock mechanism is defeated to open a compartment door.

7. Current transformer primaries must not be energized when secondaries are open circuited. Short all CT secondaries

For safety of personnel working on busbars, provide temporary earthing using a metallic chain/ strip near the workplace. Remove this earthing only after the job is completed


B. Periodic Maintenance:


1.All busbar joints and tap off points to be periodically checked by torque wrench for their tightness at least once in a year.

2.All dust and foreign material should be removed.

3.All cable connections to MCCB/ISOLATOR should be properly tightened to avoid any undue stress on the terminals on for better contact pressure to avoid localized heating. Periodical checking of the contact should be done. Check for damage or pitting of contact of ACBs, MCCB’s and Contactors. It is advised to follow the respective instruction manuals of manufacturers of these components.

4.Periodical tripping and closing/opening of circuit breaker should be checked qualified maintenance person, if found not in order the circuit breaker should be replaced.

5.All removable covers to be checked for proper fixation and damage of gasket to avoid ingress of dust and vermin.

6.Check for damage of any shroud and guard while operation.


7.Check for trouble free operation of electrical components by manual operation on no load.


8.Ensure that all shrouds and guards are replaced to their original position after maintenance.


9.Ventilation provided on the panel should not be blocked periodical checking of the air vents to be taken care for proper air circulation there by minimizing heating of the component.


10. The operation of system can be checked as per the drawings enclosed.


11.The maintenance and operation of panel should be carried out in the supervision of qualified engineer duly authorized by electricity authority.


12.For the requirement of spares / components please refer to the drawing / BOM provided with the panel / enclosed.

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