Patent ID: 7333308
Filing Date: 2008-02-19
Classification: H01H,H02H

Abstract:
1. An arrangement comprising: a DC motor, current supply means, an electrical relay through which current is supplied, in use, from the current supply means to the motor, and control means operable to provide a relay make signal and a relay break signal to control the state of the relay to respectively make and break a connection to the current supply means, wherein the control means is further operable to enable or disable the current supply means and includes first delay means operable to delay enabling the current supply means until after a relay make signal has been provided, to allow the relay to make the connection before current supply commences, and second delay means operable to delay a relay break signal until after the current supply means has been disabled, in the event that current supply to the electrical relay is to cease, and wherein the arrangement further comprises current sensing means operable to measure the current being supplied by the current supply means and the control means is operable to test whether the magnitude of the current exceeds a predetermined limit and, if so, disable the current supply means for a predetermined time and, at the end of said predetermined time, test whether the magnitude of the current exceeds said predetermined limit.