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Questions and Answers
Low voltage is defined as?
Low voltage is defined as?
What instrument is used to carry out a polarity test?
What instrument is used to carry out a polarity test?
When carrying out a polarity test what is the maximum acceptable voltage reading between neutral and the reference earth?
When carrying out a polarity test what is the maximum acceptable voltage reading between neutral and the reference earth?
What is the maximum acceptable value of Loop Impedance without reporting or referring to a supervisor at the ESB/customer interface (Isolator)?
What is the maximum acceptable value of Loop Impedance without reporting or referring to a supervisor at the ESB/customer interface (Isolator)?
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In a Three phase MV to LV transformer winding configuration is?
In a Three phase MV to LV transformer winding configuration is?
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An open circuit in the neutral of a single phase service to a customer with a TNCS (neutralised) earthing arrangement is most likely to result in?
An open circuit in the neutral of a single phase service to a customer with a TNCS (neutralised) earthing arrangement is most likely to result in?
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What type of protection is a low voltage sub (transformer) fuse designed to provide?
What type of protection is a low voltage sub (transformer) fuse designed to provide?
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The person responsible under the ESB safety rules for assigning the PICW is?
The person responsible under the ESB safety rules for assigning the PICW is?
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The close proximity zone radial distance for low voltage as outlined by the ESB safety rules is?
The close proximity zone radial distance for low voltage as outlined by the ESB safety rules is?
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The low voltage supply standard is?
The low voltage supply standard is?
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The radial distance of close proximity to medium voltage (10 / 20kV) is?
The radial distance of close proximity to medium voltage (10 / 20kV) is?
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The person responsible under the ESB’s safety rules for the application of local earths is?
The person responsible under the ESB’s safety rules for the application of local earths is?
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A hold-off notice is required at?
A hold-off notice is required at?
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Study Notes
Low Voltage Definitions
- Low voltage is typically defined as a voltage not exceeding 1000 volts a.c. between phase and earth or 1500 volts between phases.
Polarity Testing
- A polarity test is conducted using a Digital Voltmeter.
- The maximum acceptable voltage reading between neutral and the reference earth during a polarity test is 1 Volt.
Loop Impedance
- The maximum acceptable value of Loop Impedance without needing to report to a supervisor is 0.5 Ω.
Transformer Configurations
- Common three-phase MV to LV transformer winding configurations include:
- Primary Delta: Secondary Star
Neutral Circuit Issues
- An open circuit in the neutral of a single-phase service in a TNCS earthing arrangement can cause the customer's exposed conductive parts to become live.
Low Voltage Substation Fuses
- Low voltage transformer fuses are designed to provide short circuit protection.
Personnel Responsibilities
- The system controller is responsible for assigning the Person In Charge of Work (PICW).
- The PICW is also responsible under ESB safety rules for the application of local earths.
Safety Zones
- The close proximity zone radial distance for low voltage is defined as 0.5 meters.
- The radial distance for close proximity to medium voltage (10 / 20kV) is set at 0.75 meters.
Hold-Off Notices
- A hold-off notice is mandated at every point of disconnection and main earth for safety compliance.
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Description
This assessment is designed for the Level 1 Operations Training Programme (Code- NTOPS-L1-01). It consists of 50 questions, where specific questions must be answered correctly to pass. Achieving a minimum of 70% with all marked questions is required for certification.
