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Restricted Electrical Licence

Restricted Electrical Licence. Voltage Measurement. Lesson 6. Voltage. Do we need to MEASURE it?. OR. Do we need to DETECT it?. Voltage Detection Devices. Test Lamps Neon Test Pencils/Screwdrivers Voltage Probes Steinel Combi -Check AC Voltage Probe. Voltage Measurement Devices.

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Restricted Electrical Licence

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  1. Restricted Electrical Licence

  2. Voltage Measurement Lesson 6

  3. Voltage Do we need to MEASURE it? OR Do we need to DETECT it?

  4. Voltage Detection Devices • Test Lamps • Neon Test Pencils/Screwdrivers • Voltage Probes • SteinelCombi-Check • AC Voltage Probe

  5. Voltage Measurement Devices • Voltmeter • Multimeter • Clamp meter • Analogue • Digital • Digital simulated Analogue

  6. Handheld Test Tool Safety Last known earthly residence of automotive fuse used to replace original fuse Test leads survived intact

  7. Handheld Test Tool Safety Test leads destroyed 13.8 kV arced over to test probes

  8. Handheld Test Tool Safety Fingerprints burned into probes 250V fuse didn’t open in time Poor quality leads and probes led to injury. Probe tips burned off

  9. Handheld Test Tool Safety

  10. Common Hazards • Arc from transients (lightning, load switching) • Voltage contact while in continuity or resistance • Measuring voltage with test leads in current sockets • Shock from accidental contact with live components • Using meter or tester above rated voltage

  11. Transients Protection Independent certification to meet CAT III-1000 V or CAT IV 600 V

  12. Voltage Measurement When Set to Ω Protection Overload protection in Ω up to the meter’s volt rating

  13. Voltage Measurement When using current Sockets Protection High fault current rated fuses Use meters / testers without current sockets

  14. Accidental Contact Protection Test Leads • Double insulated • Recessed / shrouded Plugs/Sockets • Finger guards • CAT III – 1000 V • Replace when damaged

  15. IEC IEC 61010 • New standard for low voltage “test, measurement and control equipment”. • Provides much improved protection against “overvoltage impulse transients” - voltage spikes. • Basis for: • ANSI/ISA-S82.01-94 (US) • CAN C22.2 No. 1010.1-92 (CAN) • EN61010-1:1993 (EUR) • AS 61010.1:2003 (Testers) • AS 61010.031:2004 (Leads)

  16. Category Levels The closer the location is to the power source, the higher the available fault current, the higher the category • CATEGORIES: CAT I to CAT IV • The greatest danger from transients is in the high categories, because they could trigger an arc blast • IMPULSE TESTING: No failure allowed • Meters must be tested by being hit with a specified number of transients, with specified peak voltages

  17. Category Levels • CAT IV • CAT III • CAT II • CAT I • “Origin of installation”Supply Authority level and any outside cable runs • Distribution wiring, including Consumer mainsand Sub-circuits; permanently installed loads. • Socket Outlets; plug-in loads. • Protected electronic circuits

  18. Category Levels

  19. Category Levels • WITHIN each Category: • There are designated “working voltages” (50, 150, 300, 600, 1000 V). • A higher voltage has a higher transient withstand

  20. Category Levels • CAT IV • CAT III • CAT II • CAT IV – 600 V: 8 kV impulse • CAT III – 600 V: 6 kV impulse • CAT III – 1000 V: 8 kV impulse • CAT II – 600 V: 4 kV impulse • CAT II – 1000 V: 6 kV impulse

  21. Cat III-600V or Cat II-1000V? The greater the source impedance, the lower the category: • CAT III-600 V = 6 kV impulse • 2 ohm test source • CAT II-1000 V = 6 kV impulse • 12 ohm test source A CAT III-600 V 6k V test impulse has 6 times the current of a CAT II-1000 V 6 kV test impulse!

  22. Cat III-600V or Cat II-1000V? First know the category you are working in, then choose the appropriate voltage rating If you ever measure power circuits, you should use: CAT III-600 V OR CAT IV 600 V OR CAT III-1000 V • AND CAT IV 600 V ORCAT III-1000 V test leads

  23. Meter Markings No meter is safe when improperly used CAT IV-600 V CAT III-1000 V CAT III-600 V CAT III-1000 V

  24. Meter Test Leads • Don’t let test leads be a weak point • CAT III-1000 V or CAT IV 600 V/CAT III 1000 V rating • Double insulation • Shrouded connectors • Finger guards • Insulation not damaged: not melted, cut, cracked, stretched • Connectors: no insulation pulled away from end connectors • Probe tips: not loose or broken off (too short)

  25. Meter Testing Safe practices include but are not limited to: • Whenever possible, work on de-energized circuits. • Follow proper Isolation procedures. • Use well maintained tools and appropriate safety gear • Safety glasses, insulated tools, insulating gloves, flash suits, insulating mats, etc. • Don’t work alone. • Practice safe measurement techniques. • Always connect the EARTH FIRST, ACTIVE SECOND. • Disconnect the ACTIVE lead first, EARTHED lead second.

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