250VDC Magnet Safety Disconnect Switch

Download Operator Control and Safety Disconnect Switches Information Sheet

Magnet circuits, which are highly inductive, occasionally require disconnection while the magnet is energized. Standard knife or safety switches are not capable of breaking this highly inductive magnet energy. Ohio Magnetics’ magnet disconnect switch interrupts the magnet circuit by using a quick break switch with a permanently connected power diode and power resistor* across negative and positive of the switch output. The power diode directs the discharge current from the negative to positive while blocking the normal currents from positive to negative. The power resistor* dissipates the stored energy of the inductive magnet circuit. The switch is polarity sensitive. Input and output power leads must be connected as indicated by markings.

Standard Features

  • Manually operated

  • Automatic discharge of magnet power

  • Mechanical interlock (door must be closed to operate)

  • NEMA 3R/12 (IP-55) combination enclosure

  • Provides operator safety

Ohio Silicon Rectifiers

Download Ohio Silicon Rectifiers Information Sheet

Ohio Magnetics’ DC Power Supplies for lifting magnets are available in both a fixed voltage output (usually 230 VDC or 115 VDC) and a variable output (usually 0-230 VDC or 0-300 VDC). Fixed voltage output type DC Power Supplies are used in most general magnet applications. Variable voltage supplies are used in applications of fanning, boost/carry, flux reduction, constant flux regulation, etc. Voltage outputs can be set via potentiometers for voltage limit-current regulation or current limit voltage regulation. Because the cold current of the magnet is 30% to 50% greater than the operating current, the power supply must be sized for the cold rating of the magnet at 25º C.

  • NEMA 12 (IP-55) enclosure natural convention

  • North American or international input voltages; 3 phase; 50 or 60 Hz

  • 480 V or 240 VAC input voltage, 3 phase, 60Hz

  • Magnetic line starter with 3-phase overload relay protection

  • Adjustable taps on power transformers to match input line conditions

  • Fast acting fuse protection for diode bridge

  • Transient surge protection/ DC output fuses for short circuit protection

  • AC power on indicator light (neon)

  • Wall mounted enclosures to 10 KW, floor mounted enclosures above 10 KW

  • 110/120 V (North America) or 220/240 (international) control voltage for input switching and operation of accessories

  • 120 VAC control for input power switching

  • Input and output power terminal blocks

  • 230 V or 115 VDC output voltage (115 VDC output only to 25 KW)

  • Modular diodes/scr’s for easy replacement

  • Convection cooled up to 6.5 KW (230 V) or 4 KW (115V); Fan cooled above 6.5 KW (230 V) or 4 KW (115 V)

  • Separate 230 V supply for controllers on all variable voltage supplies

  • Optional Features include IP32, IP66, enclosures natural convection and Latch lock on enclosures where possible

Emergency Power Supplies [Battery Back-Ups]

Download Battery Back Ups & Emergency Power Supply Information Sheet

Ohio Magnetics’ on-line type emergency power supplies provide instantaneous backup power to 230 VDC lifting magnets that will safely hold loads in the event of a power failure for your specified period of time. Available for 2 KW to 100 KW Magnet systems, OHIO EPS power supply also provides instant warnings that the magnet system is operating on battery power in both audible and visual displays.

Standard Features:

  • 5, 10, 15, 20, 30, 45 and 60 minute holding times

  • Lead Acid industrial batteries in a separate enclosure

  • Batteries charge from main power

  • Instant transfer to-on-line battery power

  • Battery disconnect switch with fault sensing

  • NEMA 12 control enclosures

  • Local display with alarm horn and visual operation indicating lamps

  • 180 VDC end voltage

Optional Features:

  • Nickel – cadmium batteries

  • Boost and Trickle Charging

  • Separate battery charger

  • Remote Display with visual alarm, audio alarm, lamps, meters

  • 115 VDC system voltage

  • Optional Battery enclosure heaters

Additional Magnet Control Equipment

  • Under Current Alarm Package

  • Reduced Voltage Relay Panel

  • Various Control Switches

  • Resistor & Meter Packages

  • Surge Suppressors

  • Warning and Alarm Devices

  • Magnet Monitoring Equipment

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