Overload and Protection Relays

Industrial Protection & Control: Efficiency and Safety

Henvi’s industrial protection and control range has been designed to provide complete control over the electrical and mechanical systems within your infrastructure. As specialist distributors, we bring together in a single catalogue the essential components to ensure that your industrial operation is not only productive, but also resilient to failures and safe for all operators.

Control Components for Precise Automation

Industrial control is the brain of any electrical panel. At Henvi, we supply devices that enable direct interaction between people and machines, as well as the automatic control of loads:

• Power Contactors: For starting and stopping motors and large loads.
• Push Buttons and Signalling Devices: Control buttons, emergency stops and indicator lights for local control.
• Control Relays: For auxiliary logic and thermal protection of equipment.

Industrial Protection Against Electrical Faults

To protect your most valuable assets, Henvi selects protection devices that respond quickly to abnormal operating conditions:

Motor Protection: Motor circuit breakers and thermal overload relays that prevent damage caused by overloads or phase failure.

Technical Selectivity: Ensuring that only the affected area is isolated, keeping the rest of the installation operational.

Durability: Equipment designed to withstand intensive switching cycles in factory environments.

The Ideal Partner for Control and Protection Projects

At Henvi, we understand the challenges faced by maintenance technicians. That is why we offer more than electrical equipment: we provide technical specification support. Whether you need to size a starting system for a pump or configure a control console, our team ensures that you receive the right components, with the necessary European certifications and immediate stock availability.

Frequently Asked Questions About Protection & Control

What does industrial protection and control cover?

This area encompasses all devices that control the flow of energy (control, such as contactors and push buttons) and those that protect equipment and people against electrical faults (protection, such as motor circuit breakers and relays).

What is the importance of integrating protection and control in the same panel?

Integration allows the control system to monitor the status of the protection system. For example, if a motor overheats, the protection device can send a signal to the control system to stop operation and indicate the fault with a warning light, preventing further damage.

Are Henvi control devices compatible with automation systems?

Yes. Our contactors and control devices are compatible with industrial standards, allowing integration with PLCs (programmable logic controllers) and other centralised technical management systems through universal coils and auxiliary contacts.

Thermal Overload Relays (LRD) for Motor Protection

A thermal overload relay (LRD) is an essential electrical device designed to protect electric motors and other equipment against sustained overloads and phase loss. Designed to monitor indirect motor heating through increased current, this device acts by disconnecting the control circuit, preventing overheating and damage to the motor windings.

Advantages and Features of LRD Thermal Overload Relays

Henvi's catalogue brings together overload trip solutions designed for direct coupling to contactors:

• Flexible Adjustment Range: Precise selection of the rated current using a front selector (e.g. 0.63A–1A, 1A–1.6A, 5.5A–8A, up to high industrial ratings such as 115A).
• Test and Reset Functions: Integrated STOP and RESET buttons (manual or automatic) for quick technical intervention.
• Integrated Auxiliary Contacts: Standard configuration with 1NO+1NC contacts for contactor disconnection and fault indication.
• Connection Options: Models with traditional screw terminals or spring connection technology for environments subject to vibration.

Applications in Motor Starting and Control

LRD thermal overload relays are an essential complement to direct-on-line, star-delta and reversing motor starter circuits:

Pump and Fan Protection: Prevents mechanical rotor blockage from burning out the motor.

Phase Loss Detection: Interrupts operation if one of the phases in a three-phase network fails, preventing single-phasing.

Direct Mounting under the Contactor: Modular design engineered to fit directly onto the lower terminals of the power contactor (e.g. LC1D range), optimising space inside the electrical panel.

Why Buy Thermal Overload Relays from Henvi?

At Henvi, we know that the electric motor is the productive heart of many industries. A correctly sized and calibrated thermal overload relay is the most cost-effective investment for avoiding the enormous costs associated with motor rewinding or replacement. We offer permanent stock of the LRD series and dedicated technical support to help you select the appropriate trip class and adjustment range according to your motor's service factor.

Frequently Asked Questions about Thermal Overload Relays (LRD)

How does a thermal overload relay (LRD) work?

The thermal overload relay contains bimetallic strips that deform when a current higher than the rated value flows through them for a certain period. As they deform, the mechanism opens a normally closed (NC) auxiliary contact, de-energising the contactor coil and safely switching off the motor.

How do you set the adjustment current of a thermal overload relay?

The thermal overload relay should be set exactly to the rated current value (

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n

) indicated on the motor's nameplate for the operating voltage being used. It should not be set above this value, as this could compromise effective motor protection.

What is the difference between a motor circuit breaker and a thermal overload relay?

A thermal overload relay only protects against overloads and needs to be associated with a contactor and fuses/circuit breakers for short-circuit protection. A motor circuit breaker combines thermal protection (overload) and magnetic protection (short circuit) in the same unit, while also allowing manual disconnection.