MTL LC30 Surge Protectors

The MTL LC30 surge protector protects load cell and weighing system installations from possible malfunctions or damage to individual strain-gauge bridges or associated electronic instrumentation caused by severe overvoltages or impulse currents on signal cabling.

Weighbridges, silos and other product batching/weighing facilities are typically large metal structures, and are exposed to direct lightning strikes. Protecting the structure from lightning is not in itself sufficient to prevent the secondary damage to associated electronic systems. Individual load cells and strain-gauge bridge insulation may break down under the abrupt shift in local structural voltage as lightning currents are dissipated to local ground, thus allowing surge currents to flow through the connecting cable into the various indicators and power supplies situated some distance away. The connecting cabling can be armored, shielded, or underground and may still be susceptible to surges.

Load cells may be damaged by surges, as few transducer manufacturers make more than a token effort at incorporating protection components. Adequate protection is even more critical with digital load cells, where electronic components and amplifiers are installed right at the point of greatest exposure.

Surge protection devices protect the system at the point of installation, therefore a full system is likely to have at least one MTL LC30 device installed at the weighbridge to protect the load cell(s), and another LC30 in the weighing control cabin to protect the electronics installed there.

Fully solid-state, the LC30 clamps incoming surges immediately without causing undue leakage losses under normal conditions. Once the surge has passed, the device automatically resets to the passive state, allowing normal operations to continue. The advanced protection concept used in the LC30 also eliminates the expensive additional earthing systems specified by other suppliers, so field installation is very simple indeed.

The LC30 can be used in hazardous area applications with appropriate self-generated system documentation as it is non-voltage producing, non-energy storing ‘simple apparatus'. Our application guide details the steps necessary to achieve an intrinsically safe installation. The LC30 is designed for use in Zone 2/Div2 and is also suitable for legal metrology applications.