Drives take the biscuit

Repeated drive failures at a biscuit factory in Yorkshire, UK, caused major problems, including lost production. The original IP20 drives used at the factory were suffering from contamination, which was causing them to fail prematurely (Fig. 1).

The original IP20 inverters (typically rated 0.75kW), were driving conveyors on biscuit production lines at the Yorkshire factory. Any stoppage of the lines meant lost production - but, unfortunately stoppages were many - and costly, due to the resulting downtime and the cost of replacing the failed inverters themselves. Replacements were readily available from a catalogue retailer - however, these drives also failed - probably because, they too, were IP20 units and susceptible to the same operational problems as the original inverters.

At this stage, engineers from Lenze's local solution provider, Westin Drives, was called in to investigate the unexplained failures. They concluded that the inverters were suffering from severe infiltration of dust, which was causing them to overheat and then fail prematurely.

The solution proposed by Westin was to replace the IP20 drives with IP65enclosed SMVector inverters from Lenze. The retrofit of these drives offered a number of advantages.

First, SMVector drives are designed for mounting without a panel or cabinet, their standard IP65 rated enclosure providing protection from dust, dirt, debris, water jets, food products and diluted cleaning products.

Second, the IP65 rating meant that the biscuit manufacturer did not have to invest in control cabinets, which were both costly to buy and install, and would have increased the footprint of the conveyor control system. Third, the fact that no cabinet was required means that the drives could be positioned closer to the motors they are driving. This reduces both wiring and installation time. It also means that equipment is easier to move and reconfigure in today's flexible production environments.

Fourth, the SMV inverters solved a problem where some operators would make unwanted changes to the settings of the drive. The SMV has password protection_ this means that operators have access to the integrated display and keyboard, but cannot change the parameters of the drive without knowing the password.

Fifth and final, the SMV features a programmable EPM chip, which allows users to copy across in a matter of seconds an entire operating set of parameters to another SMV drive.

In pressurised operating environments such as food production a replacement EPM chip can often be used to return a machine to service without having to call out a support engineer, or commit skilled programming time to recommission an individual drive.

Improving the mix

Meanwhile, Baginto AB bakery in Sweden has been able to upgrade its mixing and dough preparation equipment, improving productivity and flexibility with Lenze SMD and SMVector IP65 inverter drives. The highly compact SMD drives are ideal for retrofitting in existing panels at the bakery, whilst the IP65 rating of the SMVector drives enables them to be mounted directly to stainless steel surfaces without the cost and complexity of control cabinets. In addition wiring is greatly simplified as the drives can be mounted closer to the motors they control.

The recent investment means that many areas of the bakery are now controlled by Lenze variable speed drives. The conveyors and rollers on Baginto's biscuit production line (Fig. 2) are equipped with Lenze SMD drives. The compactness of these drives makes them ideal for these applications. Supplied as retrofit units, they are providing smooth torque operation and fine speed control where machines already have control cabinets: the cabinets themselves are stainless steel due to the hygiene requirements in food production industries.

The flour mixing and dough folding equipment at the bakery also now employ variable speed operation - benefiting both the consistency and quality of the product. At these stations, the drives had to satisfy a requirement to allow manual adjustments to the mix during production. This meant that they had to be both visible and accessible, and close to the machinery that is usually moved around as part of the production process.

The IP65 enclosed SMVector drives provided the ideal solution. Their inbuilt levels of protection against contamination meant that they could be mounted directly to the mixer and the rollers, onto stainless steel frames, without the requirement for an additional cabinet with its attendant space requirements, additional wiring, and cost.

The SMVector drives are dust-tight, so the fine flour dust in the bakery atmosphere causes the drives no problem at all. In addition, the SMV drives are also rated against low pressure jets, from the frequent washdowns required in food production environments.

The combination of the two drive systems: Lenze SMD drives where space is limited, and SMVector drives where operational and environmental requirements meant that they were the only solution, which has worked excellently at Baginto. The bakery has been able to increase productivity and flexibility with minimum disruption, and more importantly without breaking the bank.

The SMVector range of inverter drives, is available for singlephase operation from 0.37kW to 2.2kW, and threephase from 0.37kW to 22.0kW. The SMV range removes the cost and complexity from vector-based motor control, offering fast dynamic torque response, sophisticated autotuning and impressive low speed operation from a compact, low cost and simple to use package. The SMV drive also offers ingress protection to IP65, allowing for outdoor use, operation in environments with atmospheric moisture present and protection from low pressure water jets. The SMV range is designed for use in small motor applications where dynamic speed and torque control are required, such as conveyors, food production, packaging lines and HVAC systems.

For more information, visit www.actechinternational.com

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