LIFTING MAGNET AND METHOD FOR EMERGENCY POWER SUPPLY

• US 20100219689A1
• Filed: 08/20/2008
• Published: 09/02/2010
• Est. Priority Date: 10/29/2007
• Status: Active Grant

• Current Assignee: Egon Evertz KG
• Original Assignee: Egon Evertz KG
• Inventors: Evertz, Egon
• Granted Patent: US 8,242,632 B2
• Time in Patent Office: Days
• US Class Current: 307/66
• CPC Class Codes: H01F 7/1844 Monitoring or fail-safe circuits for relays H01H47/002
• CPC Class Codes: H01F 7/206 Electromagnets for lifting, handling or transporting of magnetic pieces or material electromagnets for guidance of vehicles, workpieces B65G21/2009; for magnetic suspension or levitation H02N15/00

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.

Claims

9. A method of operating an electromagnetic grab, the method comprising the step of:

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;

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.

10. The method according to claim 9, wherein the line voltage is measured continuously by a current sensor, and the emergency power supply is connected by the relay to the grab when the measured current falls below a threshold value.

11. The method according to claim 10, wherein an acoustic or visual signal is generated whenever the receiver is not receiving the test signal to be received or whenever the current sensor detects that the amperage has fallen below the defined threshold value.

12-1. The combination defined in claim 12, further comprising:

means on the grab for charging the emergency power supply when the relay is in the normal position.

15. The combination defined in claim 15 wherein the limited time period of the receiver is shorter than that of the transmitter.