Title:
MAGNET PROTECTIVE DEVICE
Document Type and Number:
Japanese Patent JP3165381
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To prevent a magnet from being burnt or being broken down by interrupting the current to the magnet when energization command controlling signals for driving the magnet are outputted exceeding a fixed time.
SOLUTION: A magnet protective device is provided with a capacitor 6 to which a controlling voltage is applied, a resistor 7 connected to the capacitor 6 and a signal switch 8 which is off when energization command signals A-D for driving the magnet are outputted to a main power supply unit 1 to maintain the capacitor 6 in a charged state and is on when energization command signals A-D are stopped to permit discharge of the capacitor 6. The magnet protective device is also provided with a time constant circuit 3 which interrupts power supply to the magnet from the main power supply unit 1 when the voltage of the resistance 7 increasing with the amount of electricity stored in the capacitor 6 reaches a reference voltage during output of energization command signals A-D. Consequently, when cenergization command signals A-D are outputted exceeding a fixed time for some reason, the current to the magnet is interrupted to prevent it from being burned or being broken down.
Inventors:
Masaru Murakoshi
Application Number:
JP30289896A
Publication Date:
May 14, 2001
Filing Date:
November 14, 1996
Export Citation:
Assignee:
Toshiba Tec Corporation
International Classes:
H01F7/18; H02H11/00; (IPC1-7): H01F7/18; H02H11/00
Attorney, Agent or Firm:
Akira Kashiwagi (1 person outside)