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Grey Siemens 5SY41205 DIN rail supplementary protector, single pole, toggle actuator, screw clamp terminals

SIEMENS

SIEMENS 5SY41205 20 A 230/400V AC 1 Pole DIN Rail Supplementary Protector

SKU CH-KXSA-JPYG1

Single-pole DIN-rail supplementary protector rated 20 A at 230/400 V AC with 10 kA interrupting capacity and screw-clamp terminals

  • Brand nameSIEMENS
  • 20 A rated current protects circuits up to 20 A
  • 10 kA interrupting capacity clears faults at 230/400 V AC
  • Thermal-magnetic trip responds to overloads and short circuits
  • DIN-rail mounting fits standard industrial panels
  • Screw-clamp terminals accept 14 to 4 AWG wire

Industrial supplementary protector

The SIEMENS 5SY41205 is a single-pole IEC supplementary protector rated at 20 A for 230/400V AC circuits. It mounts on a standard DIN rail and uses a thermal-magnetic trip mechanism with Curve Type A characteristics. The toggle actuator provides clear on/off status for industrial control panels.

Capacity and headroom

The device carries a maximum AIR rating of 10kA at 230/400V AC and is also rated for 72V DC. Screw-clamp terminals accept conductors from 14 AWG up to 4 AWG, giving installers flexibility for various load sizes. It meets UL 1077 requirements for supplementary protection in industrial equipment.

Upgrade context

This protector replaces older supplementary breakers that lack the 10kA interrupting capacity or the dual AC/DC voltage rating. The jump is worth it when panel designs demand higher short-circuit withstand and a compact 0.69 in width per pole. It does not serve as a branch-circuit breaker for main distribution boards.

How it compares

Measured against everything we stock in Bench & DC Power Supplies, at today’s prices. Recalculated every night.

Price $43.99
Pricier than about 55% of the 677 comparable items (median $33.99).

Specifications

Product
Brand nameSIEMENS

Questions about this item

Will the 20 A 1-pole breaker coordinate with existing 10 kA rated devices on the same 230/400 V AC panel?

Yes, the 5SY41205 carries a 10 kA AIR rating at 230/400 V AC, matching the interrupting capacity of other 10 kA supplementary protectors on the same bus.

How can I verify the thermal-magnetic trip is operating correctly after wiring to the DIN rail?

Apply rated current and confirm the toggle remains closed; a controlled overload should open the toggle within the Curve A time-current band, then reset cleanly when the handle is cycled.

Does the box include screw-clamp terminals for 14 AWG to 4 AWG wire or must I order lugs separately?

The supplementary protector ships with integral screw-clamp terminals that accept 14 AWG through 4 AWG conductors; no additional lugs are required.

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