Which test is done on cable before covering?

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What Is Cable Testing, And How It's Done?
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• The purpose of power cable testing is to
  guarantee that the cables insulation is intact
  and that they operate correctly. Durability,
  high-voltage resistance, and partial discharge
  detection are tested. Poor installation causes 99
  percent of cable issues during new electrical
  equipment commissioning.
• Power cable suppliers in UAE do rigorous testing
  to ensures that any potential flaws are addressed
  before they cause more harm. They provide cable
  protection from minor lacerations to punctures
  that result in current discharge.

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Why Test Cables?

• Cable conformity
• Cabling quality
• Cable functionality
• A cable fault may often be identified before it
  becomes a problem.
• A visual inspection of your facility's wiring
  might uncover issues before they cause downtime.
  We look for copper corrosion, insulation cracks,
  dampness on wires, and other indicators of cable
  degradation.
• It is critical to ensure that cables and
  couplings are in great operating order and that
  cable problem are detected immediately.
• Cable testing should be a priority for Power
  cable suppliers in UAE to prevent and solve
  issues. Even with a range of test techniques and
  equipment, cable testing may be a challenging
  operation.
• As a result, choosing and operating the best test
  equipment is as important as the test equipment
  itself.

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What Happens When Cables Are Tested?

• The tests and inspections required before
  energizing 600V or less low voltage cable are
  given below.
• Compare the cable data to the drawings and specs.
  
• Think about the number of sets and their
  insulation ratings.
• Examine exposed cable portions for material
  degradation. Inspect the cable jacket and exposed
  insulation for damage.
• Verify that the single-line diagram's connecting
  points match.
• Check for excessive resistance using a calibrated
  torque wrench, low-resistance ohmmeter, or
  thermographic survey.
• ANSI/NETA Table 100.12 US Standard Fasteners,
  Bolt Torque Values for Electrical Connections
• Using a low resistance ohmmeter, compare the
  values of equivalent bolted connections to find
  which one moves more than 50 of the lowest
  value.
• Examine the exposed cable jacket and insulation
  on low voltage wire and cable.
• Before checking compression-applied connections,
  ensure the connector is rated for the cable size
  and has the appropriate indentations.

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• Each conductor should be tested for insulation
  resistance and ground resistance. The test must
  last one minute and utilize the manufacturer's
  recommended voltage.
• If no manufacturer information is provided, use
  500/1000 volts dc for 300/600-volt cable. To
  calculate insulating resistance, use the
  manufacturer's data. Otherwise, the values should
  be at least 100 megohmstest for continuity to
  ensure appropriate cable connection and phasing.
• Examine the resistance of parallel wires with a
  low-resistance ohmmeter. Identify resistance
  variations between parallel wires by measuring
  each cable independently.

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How Is Cable Testing Done?

• Power cable suppliers test the following things
  to avoid leakage
• Continuity Check
• The continuity test measures the low resistance
  of cables from 1 to 250 meters in length.
• The continuity test can be done with two or four
  wires, depending on the resistance to be
  measured.
• It includes injecting a preset current and
  measuring the resistance's terminals for voltage
  and current. Ohms law will decide that.
• Divide the switching matrix into two internal
  buses using the Kelvin technique.
• Directing the test current
• transmitting voltage between the element's
  terminals
• Opposing points are allocated to the
  measurement's SENSE and current injection. This
  setup is suitable with two-wire continuity tests
  and may be used throughout the switching matrix.

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Insulation Testing

• A high resistance test (insulation) is usually
  done in DC.
• This test is combined with a short circuit and
  high voltage test in DC.
• The insulation test has several uses.
• The insulation test can reveal
• calculating high voltage insulating resistances
  from 50-kilo ohm to 2000 megaohm
• Detection of short circuits and dielectric
• So, here's how it works
• A low-voltage test (continuity measurement)
  detects short circuits (1). If a short circuit is
  found, the insulation test fails (the message
  SHORT CIRCUIT appears in the error list).
• If there is no short, the high voltage is
  applied. Breakdown happens within the increasing
  time and the test is stopped (the breakdown
  voltage is given in the error list).

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• If there is no breakdown and the voltage does not
  reach the required level, the message UUprog
  displays (ten percent).
• The voltage is then supplied for the set time
• If a failure occurs within this period, the test
  is terminated, and the error time is displayed.
• To conclude the application time, the insulation
  test is done, and the insulation resistance is
  measured
• (4). An extra measurement time is added depending
  on the intended range. The measurement time
  varies from 20ms - 240ms.
• To finish the test, the tester lowers the high
  voltage and discharges the object to the ground
  (total time 20ms).
• Every insulation measurement ends with this step.
• The dielectric strength test detects any rapid
  shift in the current test increase outside the
  specified limit.
• Short circuit and high voltage testing can be
  disabled.

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Experiment With Phasing

• The proper phasing of all LV circuits must be
  verified at all locations where LV cables are
  terminated into fuse bases and while moving LV
  cables.
• This test requires specifically designed
  equipment. A 240-volt mains voltage is
  insufficient for this test.
• For this test, the neutral conductor must be
  grounded.
• Earth Resistance Test
• The earth resistance of an LV feeder in an
  overhead or underground network must be less than
  10 ohms before connecting to the existing
  network.
• Any overhead or underground network must have a
  total resistance to earth of less than 1 ohm
  before joining.

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High Voltage Test

• A/C or DC high voltage testing (also known as
  dielectric strength testing or hipot testing) In
  DC, the high voltage test is linked with
  insulation in AC, the high voltage test is more
  demanding for the sample and is done as indicated
  below.
• High voltage testing utilizes an alternating
  voltage (50Hz) adjustable from 50V to 1500V. In
  all cases, the high voltage test identifies any
  sudden increase in current up to a threshold.
• The short circuit test is always active. The time
  between application and rise is at least a
  period.
• The capacitance of the tested equipment penalizes
  the high voltage test. Remember that the
  generator's output is limited to 5 mA.

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The Advantages of Cable Testing

• Limited product warranties are available.
• Repair is more costly than testing.
• Testing regularly will ensure that the
  infrastructure is future-proof.

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Conclusion

• Since cables are the most expensive equipment in
  an installation, they must be thoroughly tested
  using the methods listed above.
• Power cable suppliers install the cable in the
  proper directions, particularly in curvatures, to
  avoid bending and kinking and improve power
  transmission and avoid losses during
  transmission, thereby increasing the cable's
  reliability and suspension.

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