The MLG-4 series of Type 4 light guards from Mechan Controls are through-beam photo-electric machine guarding devices, designed to protect operators working at or near dangerous machinery
The new light curtains from Mechan Controls are suitable for use in CAT4, SIL3, and PL-e installations. The company says that when correctly installed on a suitable machine, the system will detect a person (or part of a person) entering a dangerous area in the vicinity of a machine and will cause dangerous motion to cease before that person can reach a position where injury could occur. When designing the MLG-Series, Mechan states that its engineers had two primary goals in mind. Firstly, the new devices had to be durable and reliable enough to survive hazardous conditions found in heavy industries (such as aggregates and steel works), and secondly, they had to be cost effective.
A wide selection of beam resolutions and protection lengths make the MLG-Series suitable for applications that require simple ON/OFF detection. Protection lengths from 0.2m to 1.8m are available with beam resolutions from 14mm to 70mm: protection lengths can vary depending on the beam resolution required.
14mm resolution meets the requirements for finger protection. Due to the high resolution, the available protection height available ranges from 200mm-1200mm, increasing by increments of 200mm.
30mm resolution meets the requirements for hand protection. The protection heights available range from 200mm-1800mm, increasing by increments of 200mm.
70mm resolution meets the requirements for body protection. The protection heights available range from 200mm-1800mm, increasing by increments of 200mm.
Multi-beam resolution meets the requirements for full body access / entry detection. The protection heights available range from 600mm-1200mm, increasing by increments of 300mm.
The MLG-Series meets the requirements for Type 4. They achieve this by using OSSD outputs that continuously cross check for faults and errors. If a problem occurs, the MLG-Series will notice it immediately and send a signal to the machine, sending it into shutdown mode. The machine won’t resume until the affected part has been inspected and possibly replaced and the system has been reset.
Each MLG-Series comes with two OSSD outputs that are capable of switching 200mA. They feature ultra-fast 20ms response time ensuring immediate detection when a beam is interrupted. Housings are manufactured in metal and painted yellow and the overall product is proven to IP65 having undergone extensive testing on applications with high vibrations. All MLG-Series products come with a special dot matrix display built onto the bottom of the light curtain, which significantly improves the diagnostic capabilities by displaying its status.
If everything is OK, the light curtain will be green and present the message ‘Light curtain OK’, but if it has detected something, it will turn red and also clearly display which of the beams has been interrupted. Mechan highlights the advantages of this visual signal for operators who may be experiencing nuisance tripping somewhere in the system and need to readily identify exactly where it is occurring.
The MLG-Series has been designed to work with most OSSD compatible safety control devices but can also be used with Mechan Controls’ GM1 expandable safety relay. This expandable safety relay is designed to safely monitor the MLG-Series range of light guards as well as other OSSD compatible devices and the modular design means 20+ light guards can be installed on a single system, achieving CAT4, SIL3, PL-e.
The GM1 is non-programmable, meaning it is ready to use straight out of the box. It also offers diagnostic features including individual safety input monitoring to alert the user about which channel is faulty (traditional safety relays often just go into fault mode, leaving it up to the user to diagnose the fault manually).