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Siemens 5SY4340-8FA — Miniature Circuit Breakers (MCB)

Siemens 5SY4340-8FA SENTRON MCB, 40 A, 3P, D-Curve, 10 kA

MPN5SY4340-8FA

Siemens SENTRON 5SY4 series, miniature circuit breaker, 3-pole, 40 A, D tripping characteristic, 10 kA breaking capacity at 400 V AC per EN 60898, 440 V AC multi-phase rated voltage, IP20 with connected conductors, 3 MW units wide.

Siemens 5SY4340-8FA datasheet (PDF)
Source DocumentedChannel stated on listing & quote
Condition PhotosReal unit photos / video on request
WhatsApp AnswersFast human replies for machine-down parts
Worldwide DispatchDHL/FedEx — transit quoted per order
Independent China distributor & sourcing agent· Listing updated Sep 2026

Specifications

5SY4340-8FA — Ratings
ParameterValue
Overvoltage categoryIII
5SY4340-8FA — Mechanical
ParameterValue
Width54 mm
Height90 mm
Depth76 mm

Product details

The Siemens 5SY4340-8FA is a SENTRON miniature circuit breaker (MCB) with a D tripping characteristic, rated 40 A at 35 °C, 3-pole construction, and a 10 kA breaking capacity per EN 60898 at 400 V AC. Multi-phase operating voltage is 440 V AC. The IP20 rating applies once conductors are connected — standard for enclosed panel installation.

The 40 A rating holds at 35 °C ambient. At 40 °C it derates to 38.08 A; at 45 °C to 37.08 A; at 50 °C to 36.08 A; at 55 °C to 35 A. Maximum ambient is 75 °C, minimum -40 °C.

Depth is 76 mm, height 90 mm, width 54 mm (3 MW). Installation depth 70 mm. Sealable design allows lockout/tagout on the toggle.

Frequently asked questions

Where can I buy 5SY4340-8FA and how do I get a price?

This part is sourced and quoted to order against an RFQ through independent distribution. Submit an RFQ for current availability and pricing — no stock count or price is published here.

What is the D-curve on this MCB used for?

The D tripping characteristic (10 to 20 times In) is designed for circuits with high inrush currents — motor starters, transformers, welding equipment — where a B or C curve would nuisance-trip on startup.

What is the breaking capacity of the 5SY4340-8FA?

10 kA per EN 60898 at 400 V AC. That is the rated short-circuit capacity for the MCB — it can safely interrupt faults up to 10 kA without welding or rupturing.

Will 5SY4340-8FA drop into a panel that was specified around 5SY7210-7CC without rewiring?

Both are 3-pole SENTRON MCBs on the same DIN-rail footprint (3 MW wide), so mechanical fit is identical. The 5SY4340-8FA is a 40 A D-curve; the 5SY7210-7CC is a different rating and curve — verify the branch circuit's load and coordination before swapping.

MPN
5SY4340-8FA