Catch Trouble Before Trouble Catches You: Speed Monitoring on Conveyors helps improve the efficiency and safety of your operations…
Conveyors can fail for a variety of reasons. Bulk raw materials such as grain or rocks may be damp or wet – significantly adding to the weight on the conveyor belt and ultimately leading to belt slippage and slowdown. Conveyor belts can break due to overload, wear and tear, or the motor driving the conveyor may fail. Any one of these scenarios, if left unattended, can lead to lengthy stretches of costly downtime and wasted product. The clean up along with the time taken to carry out repairs can be much more extensive than would have been the case had a speed switch been in place. In the worst case scenario, a fault condition in a hazardous environment may lead to a situation that could endanger both people and property. Speed switches are used to help maintain the operational integrity of these conveyors and are a critical component of any safe and efficient operation. It is vital in many cases that a relatively constant speed is maintained – if a conveyor was to experience unwanted slowdown or even complete stoppage, the results could be disastrous and dangerous. Product waste, machine damage, missed deadlines, costly process downtime, and even unsafe working conditions can all be attributed to conveyor failure.
Speed switches come in a variety of forms each designed to fit a particular application covering virtually every conveying situation. There are two piece systems, three piece systems, systems designed for explosion proof environments, corrosive environments, and dirty, dusty and greasy environments – all with the same end result in mind – to protect the operational integrity of the conveyor and larger industrial process.
Speed switch systems usually monitor rotation on the tail (or non-driven) pulley via a pulse generator (usually a pulser disc or wrap with alternating polarity magnets set around the perimeter) and sensor, which in turn connects to a switch/relay module. The operator calibrates the set point (trip point) at the module using either a rotary dial or potentiometer. The set point is usually set at about 90% of operating speed (RPM) so that when a fault condition occurs, the switch will trip the relay shutting down the conveyor or activating some type of audible or visual alarm.
Electro-Sensors, Inc is a leading manufacturer of industrial speed monitoring equipment; their speed monitors can be used anywhere that there is a rotating shaft. Electro-Sensors speed switches are commonly installed on a broad range of conveyors covering almost every industrial process whether moving bulk raw materials from truck to storage facility, conveying component parts along a production line, or moving and sorting packages in a logistical hub.
Typical Application
A typical application example would be a belt conveyor conveying crushed rocks from one part of a quarrying operation to another. It is critical that the operator receives feedback as soon as the integrity of the conveying system is compromised. The conveyor runs at approximately 100 RPM and the operator needs to know if the tail pulley speed drops to 90 RPM or below – any slowdown of 10% or more could indicate conveyor overload, belt breakage, or motor failure leading to catastrophic results.
This application requires a speed switch system that is simple to install and easy to calibrate for monitoring the speed of the conveyor system. The sensor and switch electronics must be unaffected by moisture, dust, grime and grease, and be in a rugged cast aluminum housing designed for use in a harsh environment where falling rocks are commonplace. The system provided by Electro-Sensors was a 2-piece system comprising of a UL listed speed switch with a set point range between 10 and 100 RPM and a 4” aluminum pulser disc to generate pulses (M100 with 255A pulser disc). Installation was made on the tail pulley of the conveyor; the disc was end-mounted on the rotating shaft to be monitored, and the switch was installed adjacent to the face of the disc. The speed switch accepts an input voltage of 115vac, readily available in most industrial settings and has a form C relay that can be wired to a PLC, alarm circuit, or motor shutdown in the event of a fault condition. The M100 speed switch with the 255A pulser disc is a self-contained system; rugged, reliable, simple to install and calibrate, and designed to operate in a harsh environment.
Benefits
The M100 speed switch system is an economical solution to the plant’s speed monitoring problem. It ships from stock and combines ease of use along with simple, quick installation to avoid lengthy process downtime. The system is delivered onsite complete, requiring minimal additional components to install and will require minimal maintenance during normal operation. When installed, the system is designed to alert the operator when a fault condition occurs enabling a prompt response. The safety and efficiency of the plant and operators is enhanced by having a speed switch installed to provide an early warning system when machinery fails. Prevention of just one incident would, in most cases more than cover the cost of purchase and installation of several speed switch systems.
