Drive circuit for a main contactor
AssigneeSiemens Aktiengesellschaft
InventorsWerner Meier, Rudolf Schmidt, Martin Kraft
Life of this patent
Estimating the term…
Abstract
A drive circuit for a main contactor which opens the contactor when a voltage dip occurs and if the voltage dip is of short duration closes the contactor again but blocks reclosing if the voltage dip persists. The circuit includes means to form an undervoltage pulse which has a duration which is equal to the length of time an undervoltage is present or a predetermined maximum time which ever is shorter. As long as the undervoltage pulse is shorter than the predetermined maximum the contactor is again closed but should the undervoltage persists beyond the predetermined maximum pulse length the drive circuit is allowed to become permanently disabled until further action is taken.
Claims5
In a drive circuit for a main contactor of the type which converts control commands from a command control transmitter into positioning commands for coupling contactors which switch the main contactors ON and OFF and which includes an end position error monitor forming end position error signals by comparing positioning command stored in command storage units with return signals from signalling contacts of the main contactor the improvement comprising:
- a. means for monitoring an undervoltage of the control voltage of the main contactor and providing a protection command output which is coupled to switch off the main contactor if the voltage falls below a specified limit;
- b. means for forming an undervoltage pulse output which begins with the occurence of the protection command and has a length which is the shorter of the length of the protection command and a predetermined maximum duration;
- c. first blocking gates coupling the end position error signals to the command control transmitter, said gates having said undervoltage pulse output as disabling inputs;
- and
- d. second blocking gates coupling the command storage units to inputs from the command control transmitter and having as disabling inputs said undervoltage pulse output.
Dependencies are inferred from the claim text.