BS 5611:1978

National foreword
Cooperating organizations
1. Scope
2. Selection of a tap-changer
2.1 General remarks
2.2 Insulation level
2.3 Current
2.4 Breaking capacity
2.5 Number of tapping positions
2.6 Discharge problems with change-over selectors
2.7 Mechanical life
2.8 Motor-drive mechanism
2.9 Pressure and vacuum tests
2.10 Low-temperature conditions
2.11 Continuous operation
3. Location of oil-immersed tap-changer components
3.1 Tap selectors
3.2 Diverter and selector switches
3.3 Oil level alarm contacts
4. Field service
4.1 Safety of operation
4.2 Parallel operation
4.3 Contact erosion and oil contamination
5. Information required with enquiry or order
5.1 Rating and general data
5.2 Insulation level
5.3 Pressure, vacuum and temperature requirements
5.4 Special
5.5 Fittings
5.6 Motor-drive mechanism

Assists in the selection of on-load tap-changers for use with the tapped windings of transformers or reactors. Recommendations are not mandatory and only represent advice to the tap-changer manufacturer and purchaser. The responsibility for the correct application of the fully assembled tap-changer in connection with the transformer is with the manufacturer of the transformer. Includes mechanical life, pressure and vacuum tests, low temperature conditions, oil level alarm contacts, information required with enquired with enquiry or order.