BS 587:1957

Hand operated and automatic types used with a.c. and d.c. motors of rated voltages up to 11 kV a.c. and 650 V d.c. Resistors, auto-transformers and similar associated equipment. Ratings, sizes, design and construction, temperature rise limits, type and routine tests, resistor duty ratings. Appendices on temperature measurement, clearance and creepage distances, resistor duty cycles, maximum starting times.