Schneider Electric B4.85 Overload Thermal Unit Heating Element

Description

The B4.85 is a thermal overload relay heating element manufactured by Schneider Electric, designed for use with traditional NEMA-style motor starters. This component acts as the sensing element for thermal overload relays, providing essential motor protection by monitoring the current flow. When the motor draws excessive current for a prolonged duration, the heating element generates heat proportional to the current, triggering the thermal relay mechanism to open the control circuit and prevent motor damage due to overheating. It is a critical component for maintaining the operational integrity of electric motors in industrial control systems.

Features

• Thermal Sensing: Provides accurate current-to-heat conversion for reliable overload detection.
• Compatibility: Engineered for integration into standard Schneider Electric/Square D NEMA thermal overload relay housings.
• Operational Reliability: Ensures consistent motor protection performance in heavy-duty industrial applications.
• Durable Construction: Built to meet industrial standards for electrical components.

Applications

• Protection of three-phase AC motors in industrial starters.
• HVAC systems, pumps, and conveyor motor protection.
• Maintenance and repair of legacy electrical starter assemblies.
• Overload protection in motor control centers (MCCs).

Technical Specifications

Installation Guidelines

• Correct Sizing: Ensure the B4.85 heating element is correctly selected based on the motor's full-load current (FLC) rating as specified by the motor manufacturer’s tables provided for the thermal overload relay.
• Mounting: Insert the heating element into the thermal overload block, ensuring the mounting screws are tightened to the specified torque to prevent high-resistance contact points.
• Inspection: Periodically inspect the heating element for signs of discoloration or terminal looseness caused by thermal cycling.
• Safety: Always disconnect power to the motor starter before removing or installing thermal heating elements to prevent electrical shock.
• Environment: Operate within a clean, dry control panel to ensure the thermal characteristics of the unit are not compromised by ambient dust or humidity.