Method for Installation of DB or Panel-(Part-2)

(4) ELECTRICAL CHECKS BEFORE CHARGING THE  PANEL

• TESTING CONTINUITY BETWEEN ALL METAL PARTS AND GROUND
• For performing this test, it is generally recommended to use a milliohm meter for continuity measurement.
• INSULATION RESISTANCE TESTS For SWITCHGEAR
• It is recommended to perform these tests before connection starting so all isolating devices will be closed.
• If cables are already connected, open the isolating devices before any test.
• Disconnect the ground sensing device and the control cables.
• Using a 1000 V DC megohmmeter, measure the insulation resistance after a one minute Electrification time between :
• 1) Phase to Phase
• 2) Phase to Neutral
• 3) Phase to Ground
• 4) Ground to Earth
• Using a 500 V DC megohmmeter, measure the insulation resistance after a one minute electrification time between:
• 1) Auxiliary circuit and ground.
• Reconnect the cables after testing.
• Control Wiring Electrical Tests for Switchgear and Switchboards
• Perform insulation-resistance tests on control wiring with respect to ground. Apply 500 volts dc for 300-volt rated cable and 1000 volts dc for 600-volt rated cable for one minute each.
• Important: Units with solid-state components could be damaged if not properly isolated (via removal of plugs and/or fuses) before applying test voltage. Be sure to follow all manufacturers’ recommendations when performing dielectric tests on solid state components
• Minimum insulation-resistance values of control wiring should be comparable to previously obtained results but not less than two megohms.

Charging & Testing of Panel:

•  Cable Terminations:
• Identify cable to be laid and Cut the cable to required length.
• Put temporary marker onto the cable.
• Carefully pull (using suitable method) and lay the cable to its route
• Make appropriate opening (Cut-out) in DB /PANEL for inserting the cable with a rubber gasket so that there will be no sharp edges and secure the wire insulation from damage.
• Gland the cables using appropriate cable glands size.
• Terminate cables inside enclosure by securing cables to switchboards with gland bracket; and enclosure with glanding plates or fabricated steel extension boxes.
• Slice the cable and identify cores to be used. Installed the ferrule number and cable lug
• Dressing the cable inside the panel and Secure the cables (if necessary) with cable ties or other suitable method
• Install cable marker / tag as specified
• Terminate the cable properly & as per termination schedule
• Earth the glands to the equipment earth grid
• After complete termination of wire/cable same DB compartment shall be cleaned and fixed door.
• Earthing Connections:
• The Panel Main earthing bar is to connected to earth electrode or earthing Grid by Suitable size of 2 No’s of Eathing Strip or Earthing Wire via testing joints.
• Energize the Panel
• Switch off All Switchgear of Panel.
• Connect the incoming cables of Panel to the Power Supply Source.
• Check healthy ness of Power Supply at incoming of Panel.
• NO LOAD:
• Measure input Voltage of Power Supply between Phase to Phase, between Phase and Neutral and between Neutral and Ground.
• If measured incoming Voltage is within limit than Switch ON the Main Breaker of Panel.
• Measure Voltage on Bus bar between Phase to Phase, between Phase and Neutral and between Neutral and Ground.
• If measured Bus bar Voltage is within limit than Panel should operate on NO LOAD Condition for 5 minutes to observe any heating, sparking and performance of accessories of Panel.
• After 5 minute, one by one Switch ON the all Circuit Breaker of Panel.
• ON LOAD:
• Measure Voltage on each outgoing feeder of panel between Phase to Phase, between Phase and Neutral and between Neutral and Ground.
• If measured Voltage of outgoing feeders are in within limit than Panel should Energize for 2 hours and verify complete performance. Check for any unusual temperature rise in cables, terminals and protective devices.
• Correct Phasing:
• Check Phase Sequence of Power Supply at Outgoing Circuit of Panel.
• If there is not correct phase sequence for three phase power supply, reverse one phase at incoming side of Panel.
• Indicators
• Check all Power Supply ON /OFF / TRIP indicator works properly.
• If any associated converters check the indications to the corresponding output terminal block.
• Under/Overvoltage Protection
• Check the relay operation and adjust to the desired rating.
• The protection information reports shall be checked up to the distribution board output terminal block.
• Automatic Transfer Switches
• Check mechanical and / or electrical interlocks.
• With the both available supplies (Main Power & D.G Power) confirm the functional checks by presence of voltage, loss of supply, restoration of supply in manual and in automatic mode.
• The both incoming supplies are readiness in the distribution board
• Record The Test Data:

Floor Marking Near Electrical Panels:

• Keep Space in Front of Electrical Panels Clear
• The area in front of electrical panels must be kept clear and marking with effective floor marking taps.
• While specific colors of floor marking tape are not required, it’s often recommended that employers select colors that indicate a hazard is present. Striped black and yellow floor marking tape often serves this purpose, as black and yellow are regularly used for hazard markings.
• When the nominal voltage to ground for a piece of electrical equipment is 600 volts or less, the minimum depth of clear working space in front of the equipment must be 3 feet (in some circumstances, it must be larger). This distance applies to some situations involving voltages up to 2500 volts as well. 

Codes and Standards:

• Panel shall comply with the latest Relevant Indian Standards and Electricity Rule and Regulations and shall be as per IS-13947-1993.
• The general construction shall confirm to IS-8623-1977 (Part-1) for factory built assembled switchgear & control gear for voltage up to and including 1100 V AC.

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