Sensors keep Britain’s seaports running

Contrinex’s rugged Inductive sensors keep Britain’s seaports running smoothly around the clock by providing reliability switching on container-handling cranes.

Britain’s busy seaports rely upon Container-handling cranes and hence Contrinex’s rugged inductive sensors to operate around the clock. The sensors which are fitted on each hoist carriage, verify its position with respect to the crane structure and prevent it travelling outside preset limits. Because mechanical play in the hoist carriage allows a small amount of lateral drift as it travels along the crane structure, Contrinex’s long sensing distance is essential to prevent the sensor colliding with the crane structure.

Application

Loading and unloading containers in a busy British seaport is a 24-hour activity, all year round, with optimum utilisation of storage space being essential to achieve maximum operating efficiency.

Container-handling cranes operate above a storage area, positioning containers before lowering them into place. The hoist carriage on each crane travels along the length of the crane structure, traversing the width of the storage area to achieve complete coverage of the available storage space.

Inductive sensors fitted to the hoist carriage detect the ends of the structure, cutting power to the drive-motors and preventing the carriage from travelling beyond allowable limits. Mechanical play in the drive system results in the carriage drifting laterally as it travels along the crane structure. The 15mm sensing range of a competitor’s sensors proved to be inadequate; occasionally causing sensors to collide with the crane’s structure, causing damage and interrupting operation. Therefore, Continex’s inductive sensors were selected because their increased sensing range prevented collisions.

Solution

Contrinex’s ‘Basic’ range of inductive sensors are highly suited for this application. Mounted in rugged 40 x 40mm cubic polyamide glass-fibre housings, these devices from the ‘Classics’ family utilise a 20mm sensing distance that eliminates the risk of collisions. A 40mm sensing distance is also available for this sensor if needed and its IP68 / IP69K-rating makes it ideal for the outdoor working environment, even in a seaport.

The use of industry-standard housings for these Contrinex sensors ensures that they are drop-in replacements for competitor’s devices. No modification to the mounting arrangements was necessary, incurring little downtime during the changeover to the new sensing arrangements.

Communication with the crane’s control system is via a PNP changeover interface, replacing the existing two-wire arrangement; a flexible PUR-sheathed cable provides the electrical connection. The new sensor features an integral S12 connector, allowing easy removal and replacement for maintenance. The IO-Link communication protocol is also included in the sensor, although it was not used in this application.

A step improvement in operational performance was evident immediately after the new units were installed. The new sensors provide reliable sensing of each hoist’s position with no reported collisions since the date of installation. The customer has reported a marked reduction in crane downtime with an associated decrease in expenditure on replacement sensors.

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