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close this bookProtective Measures against Hazardous Contact Voltage - Course: Basic skills and knowledge of electrical engineering. Instruction examples for practical vocational training (Institut für Berufliche Entwicklung, 15 p.)
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View the documentIntroduction
View the documentInstruction Example 4.1. Preparation of a Potential Equalitation
View the documentInstruction Example 4.2. Testing of the Protective Measure of ''Protective Insulation''
View the documentInstruction Example 4.3. Testing of the Protective Measure of ''Protective Conductor System''

Instruction Example 4.3. Testing of the Protective Measure of ''Protective Conductor System''

Testing and measuring tools

Insulating resistance measuring instrument

Auxiliary means

Measuring lines, test prods

Required basic knowledge

Criteria of the protective conductor system, handling of measuring and testing tools, knowledge of measuring and testing processes, how to act after accidents caused by electric current

Sequence of operations


1. Visual inspection

- Plant has an own transformer

- Neutral point of transformer is earthed by a fusible cut-out

- All metallic pans that do not belong to the service circuit are connected with each other by a protective conductor

The protective conductor must not be connected with the neutral conductor!

2. Measuring

- The insulation resistance is greater than 25 ohms/volt

3. Functional testing

- The insulation resistance is to be reduced to a value less than 25 ohms per volt

Supervisory facility must switch off!

Testing of the protective measure of "protective conductor system"