Protection Relays

In mining operations, protection relays are important for maintaining safety, regulatory compliance, and operational continuity. At Davis & Spence, we prioritise four key factors:

• AS2081:2011 compliance: Mining standards are stringent. We supply AS2081-compliant relays and provide the technical guidance to ensure your installation meets all mandatory safety requirements.
• Operational reliability: To minimise costly downtime, we stock Littelfuse relays known for industry-leading reliability. These units include a 5-year warranty, providing long-term certainty in high-stakes environments.
• Extreme durability: Mining sites are hazardous and demanding. Our protection relays are proven to perform in the most extreme conditions, resisting the dust, moisture, and vibration common to the Hunter’s industrial sites.
• Technical support: Access to accurate information is vital. Our team provides rapid, high-quality technical support to assist engineers and technicians with relay selection and troubleshooting, ensuring your site remains protected and productive 24/7.

A protection relay is a specialised electronic device that monitors electrical parameters and triggers corrective action during a fault. It typically receives inputs from Current Transformers (CTs) or other sensors and compares these real-time signals against preconfigured safety thresholds.

If the input current exceeds these set levels, the relay provides immediate indication via a display or communicates with other electronic control systems. Importantly, it can signal a circuit breaker to isolate power, preventing equipment damage and protecting personnel. While CTs are the most common input source for monitoring current, protection relays can also utilise various other inputs depending on the specific application. At Davis & Spence, we provide the technical expertise to give you the peace of mind that your relays and transformers are correctly matched for reliable site protection.

An earth fault occurs when electrical current takes an unintended path to the ground or an equipment frame. This can result from direct inadvertent contact with an energised conductor or through capacitive earth leakage, where small amounts of current escape due to capacitive effects between high-power conductors and earth.

Regardless of the cause, identifying these faults is critical for site safety and asset protection. In any circuit, current must return to its source; an earth leakage relay detects lost current, indicating a fault. 

At Davis & Spence, we provide relays that utilise two primary detection methods: using a zero-sequence CT to monitor phase current consistency, or monitoring the connection between the transformer neutral and earth.

Our technical team ensures you have the correct relay and CT configuration to detect both minor leakages and major faults, providing a reliable defence against electrical hazards in industrial and mining environments.