ABB 1SNA684252R0200 Thermal Overload Relay (Motor Protection)

Description

1SNA684252R0200

The ABB 1SNA684252R0200 functions as a thermal overload relay designed to work in tandem with ABB contactors (such as the AX and A Series) in motor starter combinations, acting as the “safety net” for motor windings. Unlike generic fuses or circuit breakers, it uses a bimetallic strip that heats up proportionally to the motor’s current: when the current exceeds the relay’s set threshold (adjustable from 0.6A to 2.5A), the bimetallic strip bends, triggering a mechanical trip that opens the control circuit—de-energizing the contactor and stopping the motor before windings overheat.

1SNA684252R0200

This thermal-based protection mimics the motor’s own heat dissipation, ensuring it doesn’t trip during normal startup surges (which can be 5–8x the rated current) but responds quickly to sustained overloads. The relay also includes phase-loss protection, a critical feature for three-phase motors: if one phase fails, the uneven current distribution triggers an immediate trip, preventing single-phasing damage. By mounting directly onto compatible ABB contactors (via a snap-on design) and wiring into the control circuit, the ABB 1SNA684252R0200 fits into existing motor starter setups without extensive reengineering. In the motor control stack, it sits between the contactor and the motor, continuously monitoring current to balance protection and operational continuity—ensuring motors run safely while avoiding unnecessary shutdowns.

Main features and advantages:

Choosing the ABB 1SNA684252R0200 delivers tangible value that extends motor life, reduces downtime, and simplifies maintenance. Engineered for industrial reliability, its bimetallic strip is made from corrosion-resistant alloys—ensuring consistent trip performance over time, even in dusty or humid environments. This durability translates to an average service life of 8+ years, compared to 3–4 years for budget overload relays, lowering replacement costs and minimizing maintenance cycles. For engineers, the relay’s adjustable current range (0.6A–2.5A) eliminates the need to stock multiple relays for different small to medium-sized motors, streamlining inventory management. Its snap-on mounting to ABB contactors also cuts installation time by 40%: instead of wiring a standalone relay, technicians can attach it directly to the contactor, reducing wiring errors and setup complexity.

Additionally, the ABB 1SNA684252R0200’s Class 10 trip curve is optimized for most industrial motors, providing fast protection during severe overloads (e.g., locked rotors) while ignoring harmless startup surges. This balance prevents “nuisance tripping” that can disrupt production, a common issue with generic relays that use one-size-fits-all trip curves. The manual reset feature also adds a safety layer: after a trip, technicians must physically reset the relay, ensuring they investigate the cause of the overload (e.g., a blocked pump or damaged bearing) before restarting the motor—avoiding repeated damage. This compliance with IEC 60947-4-1 also helps facilities meet global safety standards, reducing the risk of fines or liability from motor-related accidents.

Application fields:

The ABB 1SNA684252R0200 excels in industries where small to medium-sized motors require reliable protection. In HVAC systems, it’s paired with ABB AX contactors to protect fan and pump motors: its phase-loss protection prevents damage if a power phase drops, ensuring heating or cooling systems don’t fail during critical periods (e.g., summer heatwaves). In food and beverage manufacturing, it safeguards mixer and conveyor motors—its dust-resistant design withstands production-line debris, and the adjustable current setting accommodates different motor sizes across the facility. In water treatment plants, it protects aeration pump motors: the Class 10 trip curve responds quickly to locked rotors (caused by debris in pumps), preventing motor burnout that could disrupt water purification processes. Across all these use cases, the ABB 1SNA684252R0200’s compatibility with ABB contactors and robust protection features make it a trusted solution for maintaining motor reliability.

Related products:

ABB 1SNA684252R0300 – Higher current range (2.0A–6.3A) for larger motors (e.g., 7.5kW–15kW pumps).

ABB 1SNA684252R0100 – Lower current range (0.1A–0.6A) for micro-motors (e.g., small conveyor or valve motors).

ABB 1SNA684252R0400 – Class 20 trip curve variant for motors with longer startup times (e.g., high-inertia fans).

ABB 1SNA684252R0500 – Automatic reset version for unattended applications (e.g., remote pump stations).

ABB 1SNA684252R0600 – Sealed (IP54) variant for dusty/wet environments (e.g., mining or outdoor irrigation).

ABB 1SNA684252R0700 – Communication-enabled model (Modbus) for remote trip monitoring (e.g., smart factories).

ABB 1SNA684252R0800 – Compatibility adapter for older ABB S Series contactors (enabling retrofits).

ABB 1SNA684252R0900 – High-temperature version (-30°C to 70°C) for cold-storage or foundry applications.

Installation and maintenance:

Before installing the ABB 1SNA684252R0200, confirm the host contactor is compatible (ABB AX 09–32, A 09–32 models)—incompatible contactors will cause mounting misalignment and wiring issues. Ensure the motor is de-energized and locked out/tagged out (LOTO) to prevent electrical shock; disconnect the motor wiring from the contactor before attaching the relay. Set the relay’s current dial to match the motor’s rated full-load current (FLC) (found on the motor nameplate)—setting it too high will compromise protection, while setting it too low will cause nuisance tripping. Clean the contactor’s mounting rail to remove debris, then snap the relay into place until it clicks—verify it’s secure by gently pulling. Wire the relay into the control circuit per ABB’s wiring diagram: connect the relay’s trip output to the contactor’s coil circuit, ensuring wires are torqued to 0.8–1.2 Nm to prevent loose connections.

For ongoing maintenance, test the relay’s trip function quarterly by manually adjusting the current dial to a value below the motor’s FLC—if it doesn’t trip, replace the relay. Inspect terminals annually for corrosion (especially in humid environments) and retighten if needed; check the bimetallic strip for damage (e.g., bending) during routine servicing.

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