TECO RHU-10/2.5K1 Thermal Overload Relay, Current Range 1.8~2.5A

TECO · RHU-10 Series · Thermal Overload Relay · 1.8–2.5A · Phase-Loss · In stock

What Is the TECO RHU-10/2.5K1?

The TECO RHU-10/2.5K1 is a bimetallic thermal overload relay designed to protect three-phase AC motors from overcurrent, phase loss, and prolonged overload conditions. It has an adjustable current range of 1.8 to 2.5 amps and mounts directly onto compatible TECO contactors for compact, tool-free installation in motor starter assemblies. Manufactured by TECO (Taiwan Electric Co.).

In short: If you need reliable, adjustable thermal protection for a small to medium three-phase motor drawing 1.8–2.5A, the RHU-10/2.5K1 is the correct part — it mounts directly onto a TECO CU-10 contactor with no brackets or additional wiring needed.

Key Features and What They Mean

1. Adjustable Current Range: 1.8–2.5A

What it means: The trip threshold is set via a rotary dial on the front of the relay — anywhere between 1.8A and 2.5A.
Why it matters: A single relay model covers motors with slightly different full-load ratings, reducing the number of spare part variants you need to stock.
Result: Flexible motor protection that adapts to your specific application without requiring multiple relay models.

2. Phase-Loss / Differential Tripping

What it means: The internal differential mechanism detects when one of the three supply phases is lost (single-phasing) and accelerates the trip response.
Why it matters: Single-phasing is one of the most common causes of motor burnout — the motor continues to run but draws excessive current on the remaining phases.
Result: Protection against the most frequent electrical fault affecting three-phase motors, preventing winding damage and unplanned downtime.

3. Direct Contactor Mounting

What it means: The relay snaps directly onto the load side of a TECO CU-10 series contactor — no DIN rail adapters, additional brackets, or wiring between the contactor and overload relay.
Why it matters: Reduces panel space, eliminates wiring errors, and cuts installation time compared to separately-mounted overload relays.
Result: Faster panel builds and fewer commissioning issues — a complete motor starter in two snap-together components.

4. Ambient Temperature Compensation

What it means: A bimetallic compensation element adjusts the trip curve based on surrounding air temperature, operating from -25°C to +60°C.
Why it matters: Without compensation, a relay might nuisance-trip in a hot enclosure or fail to trip in a cold one.
Result: Consistent protection accuracy regardless of whether your panel is in an air-conditioned control room or on a hot factory floor.

5. Selectable Manual / Auto Reset

What it means: A front-panel selector lets you choose between manual reset (operator must press the blue button after a trip) and automatic reset (relay self-resets after cooling).
Why it matters: Manual reset is safer — someone must investigate why the motor tripped before restarting. Auto reset is convenient for remote or unattended installations.
Result: One device adapts to both safety-conscious and hands-off operating philosophies.

Key Specifications

Typical Applications

• Motor Control Centers (MCCs): Standardized motor starter buckets, paired with TECO CU-10 contactors
• Conveyor Systems: Belt, roller, and chain conveyors in manufacturing and logistics
• Pumps and Compressors: Water pumps, booster pumps, small air compressors drawing 1.8–2.5A
• Fans and Blowers: Ventilation fans, cooling tower fans, exhaust systems
• HVAC Equipment: Air handling units, chilled water pumps, condenser fan motors
• Machine Tools: Lathes, milling machines, grinders

Frequently Asked Questions

"How do I set the correct trip current on this relay?"

Check your motor nameplate for the Full Load Amperage (FLA) rating — it must fall between 1.8A and 2.5A. Set the rotary dial on the front of the relay to match the FLA. If the motor runs in a hot environment or starts frequently, set the dial slightly above FLA to prevent nuisance tripping.

"Does this relay work with non-TECO contactors?"

The RHU-10/2.5K1 is designed for direct mounting onto TECO CU-10 contactors. It can be used with other brands if installed separately using an adapter base, but the simplest configuration pairs it with the matching TECO CU-10.

"Manual reset vs. automatic reset — which should I use?"

Manual reset forces investigation of why the motor tripped — safer for attended equipment. Automatic reset allows self-reset after the bimetal strips cool (2–5 min) — convenient for remote pumps or unattended HVAC. The selector switch on the front lets you change at any time.

"Can this relay protect against short circuits?"

No. The RHU-10/2.5K1 is a thermal overload relay — it protects against sustained overcurrent and phase loss. Short-circuit protection must be provided by an upstream circuit breaker or fuses. A complete motor starter includes breaker + contactor + overload relay — each handles a different protection function.

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