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. 

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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.

FLOW CHART:

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About Jignesh.Parmar (B.E,Mtech,MIE,FIE,CEng)
Jignesh Parmar has completed M.Tech (Power System Control), B.E(Electrical). He is member of Institution of Engineers (MIE) and CEng,India. Membership No:M-1473586.He has more than 16 years experience in Transmission -Distribution-Electrical Energy theft detection-Electrical Maintenance-Electrical Projects (Planning-Designing-Technical Review-coordination -Execution). He is Presently associate with one of the leading business group as a Deputy Manager at Ahmedabad,India. He has published numbers of Technical Articles in “Electrical Mirror”, “Electrical India”, “Lighting India”,”Smart Energy”, “Industrial Electrix”(Australian Power Publications) Magazines. He is Freelancer Programmer of Advance Excel and design useful Excel base Electrical Programs as per IS, NEC, IEC,IEEE codes. He is Technical Blogger and Familiar with English, Hindi, Gujarati, French languages. He wants to Share his experience & Knowledge and help technical enthusiasts to find suitable solutions and updating themselves on various Engineering Topics.

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

  1. Pradeep Maheta says:

    Excellent sir…….

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