Lifting magnet and method for emergency power supply
First Claim
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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Accused Products
Abstract
The invention relates to a lifting magnet (11), comprising an emergency power source (121) effective during a mains power failure, said emergency power source having a plurality of high-performance capacitors (12), preferably double-layer capacitors, and to a method for the emergency power supply of a lifting magnet comprising a mains voltage (10), a transmitter (32), a receiver (33) with a relay (311) and an emergency power source (121). According to the invention, the transmitter modulates a (high) frequency test signal (34) on the mains voltage, said test signal being received and evaluated by a receiver connected to the mains voltage, wherein the receiver has a relay, by means of which the emergency power source is connected to the mains voltage when the receiver does not receive the received test signal.
17 Citations
12 Claims
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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:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of operating an electromagnetic grab, the method comprising the steps of:
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normally powering the grab from a line-voltage power-supply cable; connecting a transmitter and a receiver having a relay to the cable; outputting from the transmitter into the line-voltage supply cable a high-frequency test signal; and receiving and evaluating the signal with a receiver connected to the cable and operating the relay to connect an emergency power supply to the cable whenever the receiver is not receiving the test signal. - View Dependent Claims (11, 12)
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Specification