Saturday, February 15, 2014

Thursday, February 13, 2014

Electrical Switchboard Routine Tests

  February 13, 2014 Blogger   No comments

Physical Check

·         Visual check for any physical damages on the enclosures, paint removal and breakage on components

·         Paint shade as per the approved drawings.

·         Cable feeding provisions

·         General layout of the panel.

·         Check whether all the components are fitted.

·         Check for the Labels and nomenclature

·         Size of Bus bars

Dimensional Check

·         Over all dimensions with approved drawings.

·         List of components its layouts

·         Labels descriptions

Wiring and Control Circuit Check

·         Instrument panel wiring.

·         Control circuit wiring.

·         Power wiring.

·         Protective circuits

·         Rating of breakers

·         Rated voltage of all components

·         Rating of Fuses

Mechanical Operations

·         ON/OFF operations of the circuit breakers by manually.

·         Draw out operations of the withdrawable breakers

·         Breaker interlocking mechanism

·         Electronic protection device of the breakers

·         Operations of the control components like control switches, limit switches etc.

·         Operations of the door interlocking mechanism.

Electrical Operations

·         Electrical ON/OFF operations of the circuit breakers.

·         Electrical functioning of Starters.

·         Operations of components, contactors, control relays, push buttons, indications lamps etc.

·         Checking of electrical interlocking and sequences.

·         Checking of instruments

·         Checking additional protection relays as Ground Fault & Earth Leakage

Torque Test

·         Check all joints of electrical current carrying parts to ensure the tightness by torque range

·         Bus bar joints

·         Breaker terminals

Insulation Resistance Test

·         To check the protective measure of the insulation value

·         To check the continuity of the circuits.

Dielectric Test

Dielectric Test is conducted as per IEC on the power circuits (excluding controls, instruments and electronic components etc.) The test voltage 2.5KV is applied for a period of 1 min. in between

·         1. Phase and phase

·         2. Phase and neutral

·         3. Phase, neutral and earth

 

Electrical Testing of Low Voltage Switchgear, Panelboards & Switchboards (PEARL)

  February 13, 2014 Blogger   1 comment

This "How To" electrical testing document is based on PEARL Reconditioning Standard Section 1300, Revision 5 Low Voltage Panelboards, Switchboards & Switchgear, and discusses relevant test equipment as well as suggested procedures and practices to ensure the quality, safety, and speed of your test-for-reconditioning practices.

Introduction:
The section of the PEARL Reconditioning standards covers the following several low-voltage devices including circuit breaker panelboards, switchboards and switchgear, and motor control centers. Although these devices are different in function, the inspection, reconditioning, and testing of all of these devices have enough in common that PEARL believes in appropriate to group them together under section 1300.

Test Equipment:
The following test equipment is required to perform the testing portion PEARL standards related to low voltage circuit breakers:

  1. Insulation Resistance Test Set (Megohmeter) 1000 Vdc minimum
  2. High Current Test Set

One of the following pieces of test equipment may be required to perform the testing requirements of this reconditioning standard:

  1. AC Voltage Supply
  2. AC Current Supply
  3. AC 3-Phase Voltage Supply
  4. DC Voltage Supply
  5. Digital Low Resistance Ohmmeter (DLRO - 10 amp unit is sufficient.)
  6. DC Current Source and a Millivoltmeter

Test Reference Tables:
To adequately test the electrical properties of the switchgear, panelboards or switchboards, you will also need the following technical reference documents, which can be found in the PEARL Reconditioning Standards:

  1. US Standard bus connection bolt torque values (PEARL Reconditioning Standard 6001, Table 1)
  2. Insulation resistance and test values for electrical apparatus (PEARL Reconditioning Standard 6002, Table 2)
  3. Insulation resistance and test temperature conversion to 20°C value (PEARL Reconditioning Standard 6011, Table 11)

Testing TIPS:

  • Panelboards are tested very much like a disconnect switches are tested, including the test of resistance along current carrying path.
  • It is very that the insulation between the current carriers and enclosure is solid and that nothing is escaping to a ground outside the carrying path.
  • Don't trust visual inspection as the sole inspection of insulation; a shaving, or crack in a fiberglass or epoxy insulator that is hidden from view can result in a short circuit and leave users exposed to danger.
  • Occasionally, new replacement insulators can have hidden cracks, resulting in hours of troubleshooting of a completed panelboard or switchgear. It is prudent to test replacement insulators before installation.
  • For motor controls, test each component and subassembly, including transformers, circuit breakers, magnetic contactors, and starters, which can also include integral overload devices that require testing.

Copyright :

http://www.pearl1.org/electrical-testing-tips/electrical-testing-of-low-voltage-switchgear-panelboards-switchboards_TIPS-1300.htm

 

 

Wednesday, February 12, 2014

Wednesday, February 5, 2014

IP69K

  February 05, 2014 Blogger   No comments

German standard DIN 40050-9 extends the IEC 60529 rating system described above with an IP69K rating for high-pressure, high-temperature wash-down applications.

Such enclosures must not only be dust-tight (IP6X), but it must also able to withstand high-pressure and steam cleaning.

The test specifies a spray nozzle that is fed with 80 °C water at 8–10 MPa (80–100 bar) and a flow rate of 14–16 L/min. The nozzle is held 10–15 cm from the tested device at angles of 0°, 30°, 60° and 90° for 30 seconds each. The test device sits on a turntable that rotates once every 12 seconds (5 rpm).

The IP69K test specification was initially developed for road vehicles, especially those that need regular intensive cleaning (dump trucks, cement mixers, etc.), but it also finds use in other areas

(for example, food industry, and car wash centers).

Saturday, January 25, 2014

Friday, January 24, 2014

Corrosive environment

  January 24, 2014 Blogger   No comments

ISO 12944 Classification        Typical Environments

C1                                           Heated buildings/neutral atmosphere

C2                                           Rural areas, low pollution

C3                                           Urban and industrial atmospheres

Moderate sulphur dioxide levels

Production areas with high humidity

C4                                           Industrial and coastal

Chemical processing plants

C5I                                          Industrial areas with high humidity and

aggressive atmospheres

C5M                                      Marine, offshore*, estuaries, coastal

areas with high salinity

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