Lovato SM1P0400 2.5-4 A Motor Protection Circuit Breaker

SM1P0400 motor protection circuit breaker: decoded part number

The SM1P0400 is a three-pole motor protection circuit breaker from Lovato Electric that combines thermal overload protection, magnetic short-circuit protection and phase-failure detection in one device. It is used at the head of a motor feeder, where it also acts as the manual switch and isolation point for small motors up to about 1.5 kW at 400 V.

Decoded: SM1P is the manual motor protection breaker family with the push-button operator, and the four digits 0400 identify the current range of 2.5 to 4 A. Neighbouring ranges in the family include SM1P0250 (1.6-2.5 A), SM1P0650 (4-6.5 A) and SM1P1000 (6.3-10 A).

Technical specifications of the SM1P0400

Values are taken from the Lovato Electric catalogue entry for SM1P0400. Always read the thermal setting against the nameplate current of the motor and the tripping curve.

How the SM1P0400 works

In normal operation the bimetal element heats with the motor current and trips the breaker if the overload persists, following a class 10A curve suited to ordinary pumps and fans. The magnetic release opens the three poles very quickly at 13 times the rated current in a short circuit, and the high breaking capacity of 100 kA at 400 V allows the breaker to be installed close to a strong supply; verify the prospective short-circuit current of your system before deciding on back-up protection.

Phase-failure detection makes the device trip faster when one phase is lost, which protects a three-phase motor from running single-phase. The thermal setting is adjusted with a dial inside the stated range , and the manual push-buttons give a clear on and off indication.

Fit in the system and related Lovato Electric parts

The SM1P series pairs with Lovato BF contactors, since the breaker can be mounted directly under a contactor via connecting links, forming a compact motor starter without separate wiring.

• SM1P0250 (1.6 to 2.5 A) and SM1P0160 for smaller motors
• SM1P0650 (4 to 6.5 A) and SM1P1000 (6.3 to 10 A) for the next ratings
• SM1R versions with a rotary handle, for example SM1R0400 and SM1R0650
• BF series contactors such as the BF0910A230 or BF1210A230 below the breaker

Selection and ordering checklist for the SM1P0400

Before ordering the SM1P0400, settle the following points so that the right variant is quoted:

• Motor full-load current from the nameplate: 2.5 to 4 A fits roughly 0.75 to 1.5 kW at 400 V
• Trip class and starting conditions of the driven load
• Short-circuit level at the installation point compared with 100 kA at 400 V
• Push-button (SM1P) or rotary (SM1R) operator
• Whether UL or CSA approval is needed and the UL horsepower rating

Installation, commissioning and maintenance of the SM1P0400

Mount on a 35 mm DIN rail or on a plate with screws. Connect the line and load terminals within the torque range of 2.5 to 3 Nm and dress conductors of 1 to 10 mm². Set the thermal dial to the motor nameplate current, not to the breaker maximum.

Test by operating the push-buttons and, where required, perform a primary-injection test of the trip. Record the dial setting in the commissioning sheet.

• Check terminal tightness after the first weeks of load
• Inspect for heat discolouration at the terminals
• Verify the setting after any motor replacement
• Operate the breaker a few times per year if it normally stays closed

Typical applications in Oman and the GCC

Small motor feeders for dosing pumps, fans, conveyors and cooling-water circulation pumps on oil, gas, water and power sites use breakers of this size. In Oman and GCC cabinets the temperature compensation range up to +50 °C and the operating limit of +60 °C are relevant for panels without air conditioning.

Where the cabinet ambient exceeds +50 °C, expect nuisance trips unless the current setting is adjusted or the breaker is derated, so plan the thermal margin when sizing the panel.

Variants related to the SM1P0400

The family range shown in the catalogue:

Information to send with an RFQ for the SM1P0400

To quote the SM1P0400 quickly, please send:

• Part number SM1P0400
• Quantity
• Motor nameplate current and voltage
• Short-circuit level at the installation
• Mounting method and whether auxiliary contacts are needed
• Delivery destination and date

Site conditions in Oman for the SM1P0400

Low-voltage switching and protection devices in Oman often sit in motor control centres and outdoor panels where internal temperatures are high for much of the year. When you select the SM1P0400, check its rated values at your real ambient temperature, as stated in the manufacturer documentation, and confirm the coordination with upstream protection and with the motor or load it serves. Short-circuit levels differ from site to site, so verify the breaking capacity required at the point of installation.

Standardising ratings and coil voltages across a project reduces the number of spare part numbers that need to be stocked. Keeping a small stock of the SM1P0400 and recording settings such as trip ranges or ramp times shortens repair work during a breakdown.

Documents and quotation

No datasheet file is attached to this page. Send us the part number and we will confirm which official documents are available for your application.

For a quotation on the SM1P0400, send the part number or article number, quantity and the delivery destination in Oman or the GCC. Seven Star LLC is an independent supplier based in Muscat and confirms availability and lead time per request.