Status: Need is Open

Holding Magnet for Undervoltage Release

Request Number

Point of Contact

Siemens is seeking a holding magnet, which trips/releases a fuse when a certain voltage is undercuted. Specifications for one variant of the holding magnet and further variants in the portfolio are in the voltage range between 12Vdc - 250Vdc, as well as 24Vac - 480Vac.


In the current setup, the standard deviation of the lifting force is too high which can create issues in production. Siemens is seeking a holding magnet that can perform within a defined tolerance of ± 0,5N and a defined force at the specific release voltage. The holding magnet needs to be durable (thermal) as well.

Key success Criteria

Special challenge: Small overall size, the need for a high force within a small tolerance.

Electrical requirements for new holding magnet:

Test voltage:                           70 Vdc…90Vdc

Max. Power dissipation:       325mW @ test voltage

Force:                                       8N ± 0.5N @ test voltage

Windings:                                 freely selectable regarding requirements above

Wire diameter:                        freely selectable regarding requirements above

Resistance:                              freely selectable regarding requirements above

Requirements for new circuit (if necessary):




Serial resistor:                         need to be adjusted for new coil

Capacitor:                                 need to be adjusted for new coil

Requirements device:

Nominal Voltage:                    208…230VAC

Trip voltage:                            109VAC (50% of nominal voltage)

Force:                                       8N ± 0.5N @ trip voltage

Max. power:                            <2VA @ 1.1 * 230 VAC; 115°C

Max. ambient temperature:    115°C

Surge impulse:                         2kV (IEC 61000-4-5; power port; line-to-line)

Possible Approaches

Siemens is open to all solutions that meet the success criteria. Producing the holding magnet for serial production is essential.

Due Date
Nov 8, 2019
Items to be submitted

We are looking for concise, non-confidential proposals. The proposal should:

  • Describe the technical approach
  • Provide information on the performance of the technology (if available)
  • Include a description of the responding organisation or team and their experience.

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Gallery Moderator(s)
Dezarae Carver
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