Monitoring step switch contact burning involves deriving contact burning rates from switching currents, summing, converting to contact thickness, comparing with stored limit values

摘要

The method involves permanently storing rated step voltages, limits for permissible switch and resistance contact burning and step switch-specific parameters. Switching currents for switch and resistance contacts are derived from the number of parallel sectors, the switchover resistance and the resulting current division. The burning rates are derived from the currents, summed, converted to contact thickness and compared with the stored limits. The method involves permanently storing rated step voltages, limits for permissible switch and resistance contact burning and step switch-specific parameters, determining the current switch position, incrementing an index per changeover, measuring the load current and reading out the corresponding stored rated step voltage value. The switching currents for the switch and resistance contacts being switched off are derived from the number of parallel sectors, the switchover resistance and the resulting current division. The burning rates are derived from the currents, summed, converted to contact thickness and compared with the stored limits.