ABB S203-C32 Three-pole Miniature Circuit Breaker, C 32 A

ABB’s S200 line includes the S203-C32, a three-pole MCB with the C tripping curve, catalogued as 2CDS253001R0324. It combines a delayed thermal release for overload with an electromagnetic release for short circuit, and the C curve tolerates normal switching-on surges. With a 6 kA rating under IEC/EN 60898-1, a typical job is a three-phase feeder to a 32 A load or sub-distribution board.

See circuit breakers for further protective devices, including the SACE Tmax XT moulded case breaker line above this size.

Technical specifications

Trip limits and temperature derating for 32 A

The C curve trips instantly between 5 and 10 times In, which for 32 A means 160 A to 320 A, and at 5 x In the delay is 0.1 to 15 s. Overload limits are 36.16 A for no trip over an hour and 46.4 A for tripping within an hour, the 1.13 x In and 1.45 x In points, referred to 30 C. The permitted operating current falls to 30.2 A at 40 C, 28.2 A at 50 C and 26.1 A at 60 C according to the ABB table. Grouping matters too, with factors of 0.9, 0.8 and 0.75 for two or three, four or five and six or more adjacent loaded devices.

Three-pole use and accessories

The 3P version guards all three phases from one toggle and opens them together. ABB prints 400 V AC (IEC/EN 60898-1) and 440 V AC (IEC/EN 60947-2). For remote switching and signalling there are auxiliary and signal contacts, a shunt trip, an undervoltage release and a motor operating device, plus the DDA 200 RCD block for earth-fault protection. Allow 52.5 mm of rail width and the busbar slot, which takes busbars of 10 mm2.

Reading the type code

S203-C32 reads as an S200 breaker with 3 poles, characteristic C and 32 A. The order code 2CDS253001R0324 is the number to quote on a purchase document. Please check poles, curve, current, system voltage and prospective fault current for the project, and decide on side accessories first.

Key features of the S203-C32

• Three poles that switch together, so a fault on one phase disconnects all three and avoids single-phasing of three-phase motors and loads.
• C tripping characteristic, suited to circuits with moderate inrush such as small motors, transformers, lighting groups and mixed loads.
• Thermal and electromagnetic releases in one device for overload and short-circuit protection.
• Compact 52.5 mm width for mounting on a 35 mm DIN rail in distribution boards.
• Dual rating: 6 kA under IEC/EN 60898-1 for installations and 10 kA under IEC/EN 60947-2 for industrial use.
• Compatible with the S200 accessory range for signalling and remote tripping.

Choosing between B, C and D curves

The C curve is the most common choice for three-phase sub-feeders. Confirm that the prospective short-circuit current at the installation point does not exceed the breaker’s rated capacity, and that the earth fault loop impedance is low enough for the breaker to trip within the time required by the wiring regulations.

Installation and maintenance tips

• Tighten terminals to the stated 2.8 Nm and re-check during periodic inspection, as loose connections are a common cause of overheating.
• Size the cable to the 32 A rating, accounting for grouping, installation method and ambient temperature.
• Leave spacing or ventilation where several loaded breakers sit side by side, since mutual heating reduces the effective current rating.
• Test any added auxiliary or shunt-trip accessories as part of commissioning.

Ambient temperature in Oman and GCC switchboards

Thermal releases are calibrated at a reference temperature of 30 °C, and the trip point moves as temperature inside the enclosure changes. Distribution boards in plant rooms, rooftop installations and outdoor kiosks in the region often run well above that reference in summer, so the derating information for the S200 range should be applied when the load is close to 32 A. Shading, ventilation or a cooler location for the board helps avoid nuisance tripping.

What to include in an RFQ

• Type S203-C32 and order code 2CDS253001R0324, with quantity.
• Any accessories needed, such as auxiliary contacts, signal contacts or shunt trips.
• Busbars or enclosures if a complete board is being assembled.
• Delivery location and documents required, such as test certificates.

Typical circuits protected by a 32 A three-pole MCB

In commercial buildings and light industrial sites, a three-pole 32 A breaker commonly protects feeders to small sub-distribution boards, three-phase air-conditioning condensing units, workshop machines, water heaters, pump control panels and three-phase socket outlets for portable equipment. When an MCB feeds a motor directly, it provides cable protection, while motor overload protection is normally handled by a separate overload relay or motor protection device. Coordination with upstream moulded case breakers or fuses should be checked so that a fault on the 32 A circuit is cleared locally without tripping the main supply to the whole board.

Documents and quotation

Technical data, tripping curves, derating tables, the accessory overview and the dimensional drawing are all in the ABB data sheet for the S 200 and S 200 M range linked here. Ask Seven Star LLC, an independent supplier in Muscat, for a quotation stating type and quantity. No price or stock is shown on this page; please confirm the specification before ordering.