Eaton ZB32 Thermal Overload Relay

The Eaton ZB32 Thermal Overload Relay extends Eaton's proven ZB bimetallic overload relay platform to cover the 10 A to 32 A current adjustment range, providing reliable motor overload and phase-loss protection for motor sizes from approximately 4 kW to 15 kW at 400 V AC. The ZB32 snap-mounts directly onto DILM17 through DILM32 contactors, forming compact motor starter assemblies without additional wiring, and is equally usable as a standalone unit on a DIN rail adapter for applications requiring physical separation of the overload relay from the contactor. Its bimetallic triple-element design — with one element per phase — tracks the heating of all three motor phases simultaneously, providing full phase-loss sensitivity and close thermal tracking of motor winding temperature under unbalanced supply or overload conditions. The thermal trip class 10 response is calibrated for IEC standard induction motors, coordinating correctly with the higher starting currents of 10–32 A rated motors without nuisance tripping on normal DOL starts.

The ZB32's adjustment mechanism features a calibrated dial that is set to the motor's nameplate full-load current within the 10–32 A span. The dial scale is readable with the panel closed through the relay's clear front window, allowing current verification without panel opening — a practical feature appreciated by maintenance engineers at Saudi Aramco, SABIC, and NWC plant sites where panel-closed live verification is required by electrical safety rules. A test function integrated into the relay front face allows trip function verification without disconnecting the motor, confirming relay and contactor trip wiring continuity as part of a routine preventive maintenance inspection. The reset button doubles as the test pushbutton in Eaton's ZB series design, providing a simple one-button functional test. Ambient temperature compensation is built into the bimetal calibration, ensuring accurate trip current over the 0–50°C ambient range without manual compensation adjustment — critical for sites where switchgear room temperature varies between air-conditioned office temperatures and un-air-conditioned outdoor switchgear enclosures.

The 10–32 A motor size range covered by the ZB32 corresponds to the 4–15 kW motor range, which includes the most common motor sizes in Saudi Arabia's commercial and light industrial sectors: air handling unit motors, chilled water pump feeders, cooling tower fan motors, booster pump circuit motors, and light conveyor drives. The ZB32 is specified by SEC-approved panel builders for their standard small-to-medium motor starter range, and is held as a standard maintenance spare by facilities management contractors operating residential compounds, commercial complexes, and hospital facilities across the Kingdom. Saudi Aramco's GOSP (Gas Oil Separation Plant) auxiliary motor feeder panels and SABIC's utility plant motor starters in the 4–15 kW range routinely include the ZB32 as the overload element. The 50°C ambient rating with no compensation adjustment covers all indoor and semi-outdoor switchgear locations across Saudi Arabia's climate zones.

Razz Middle East stocks the ZB32 in the ZB32-10 (6–10 A), ZB32-16 (10–16 A), ZB32-24 (16–24 A), and ZB32-32 (24–32 A) current ranges, covering the full 10–32 A span without gap. We supply project quantities to MCC panel builders and maintenance stores with same-week delivery from our Riyadh warehouse. Technical datasheets and Type 2 coordination tables pairing the ZB32 with DILM17 through DILM32 contactors and recommended upstream fuses are provided with every order, supporting project documentation for Saudi Aramco and SABIC submissions.