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Lifting magnet and method for emergency power supply

  • US 8,242,632 B2
  • Filed: 08/20/2008
  • Issued: 08/14/2012
  • Est. Priority Date: 10/29/2007
  • Status: Expired due to Fees
First Claim
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1. In combination with an electromagnetic grab normally powered from a line-voltage source having a cable with an outer end connected to the grab:

  • a plurality of high-performance capacitors on the grab, connected in parallel, and forming an emergency power supply;

    a relay at the outer end of the cable on the grab, operatively connected to the line-voltage source and to the grab, and switchable between a normal position powering the grab from the line-voltage source and not from the emergency power supply and an emergency position powering the grab from the emergency power supply and not from the line voltage source;

    alarm means activatable for generating an alarm signal;

    control means connected to the relay and to the alarm means for, on detection of a current or voltage parameter of the line voltage being below a predetermined respective threshold, switching the relay into the emergency position and activating the alarm means;

    a transmitter connected to an inner end of the cable for continuously outputting into the cable a high-frequency signal; and

    a receiver on the grab at the outer end of the cable connected to the relay for operating the relay when the receiver no longer receives the signal.

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