Mitsubishi Electric's new D700 inverter range will bring new confidence to buyers, installers and operators of variable speed drives. The new drive was developed from the highly successful 500 series range and even incorporates many features of the innovative 700 series inverters.
The D700 is being promoted as a “micro” drive, as the inverter itself is physically very small yet embodies the power, performance and features normally associated with much larger sized drives. In fact, certain drives within the range have nearly 60% less volume than their high performance predecessors. The new drive also integrates fully with other “micro” products from Mitsubishi, such as the compact FX3UC programmable logic controller and the GT1020 operator interface offering a powerful “micro automation” solution where space is at a premium.
Apart from the impressive size, the D700 will certainly attract interest from many quarters, such as system builders and manufacturing engineers who are looking to upgrade existing motor installations and get better performance from their plant. The product range covers 0.4kW to 7.5kW three phase, and 0.1kW to 2.2kW single phase. The D700 drive offers an effective drive power application for simple pump and fan control where ‘best efficiency’ or ‘energy saving’ is required to minimise power consumption through to dynamic high torque applications requiring considerable power output for moving substantial loads, either constantly or intermittently.
Manufacturers have often offered more than one product range to cope with these power control differences. In the past, this has increased uncertainty about which drive offers the best advantages. However, choice of drive can be further complicated if the application requires certain technical features of the drive, such as the ability to automatically restart after a power outage, to catch a turning load, or to cope with high overload ensuring the drive doesn’t trip. In general, drives have lined up as “light duty” with simple control against “heavy duty” with advanced control.
Mitsubishi’s new D700 inverter cuts right across these issues, offering complete power performance and advanced control in the one drive package. Thus, whether an application is high torque or high efficiency, the D700 can match the technical requirements with its comprehensive range of features. The D700 uses sensorless vector control along with advanced energy optimisation algorithm for best and most efficient performance over a wide range of demanding industrial applications. This means the drive is constantly adjusting its settings to meet the changing load requirements of the application. It is claimed to be the smallest high performance drive on the market - by a significant amount - so it is easy to install as an upgrade or retrofit.
Guy Kennett, Mitsubishi’s drives manager, commented: “We now have a single drive product that will cover all applications, from pumps and fans to conveyors and hoists - and just about any other small drive project you care to name. With it, we can guarantee optimum performance for every application; whether it needs buckets of power for shifting heavy loads and providing surges of torque when needed or the gentle touch for tweaking its settings to get maximum energy efficiency. You can draw a direct analogy with cars: for performance there is little to beat an Formula 1 car, but most of us only need performance occasionally, and are increasingly committed to fuel economy and need reliability above all else. The D700 does this in spades. Fortunately, with the D700 you don’t have to compromise one for the other.”
The design team had a number of goals when bringing the D700 to market. One of the main challenges today is energy reduction, and Mitsubishi has been able to add intelligent threshold control for a situation where the drive is running with no operational output such as a pump running at minimum speed with no real flow requirement, or a conveyor system which is running but totally unloaded for a period of time. The drive can stop the motor and be ready to come right back to speed using a fast algorithm to negate any demand dwell.
Mitsubishi has also added a drive safety stop within the drive which stops and safely removes the power from the output. The drive can be fed directly by the system safety network removing the need for separate contactors to break the mains connection in the event of an emergency.
Drives tend to be data rich these days, and the D700 is no exception. However, one feature that is sure to impress is the integration of Mitsubishi’s Graphic Operator Terminals which connects direct to the communications port. These can be fully customised to project needs giving complete graphic based, multi colour, touch screen monitoring and control. A far cry from the operational keypads normally associated with drives, and far more user friendly for operational staff.
Above all, the D700 is designed for reliable operation over many years. Mitsubishi has long championed tripless operation to ride through supply and load problems recognising that the most important aspect of any process is operational availability or reliability. This new D700 drives takes reliable operation even further by predicting the life of major components within the drive so that maintenance can be planned and action taken rather than any costly unscheduled stoppage. The D700 actively monitors its own functional operation and safety, such as initiating a warning if the cooling fan becomes erratic, monitoring the major components such as capacitors and semiconductors for age and operational usage to give a predictive life expectancy. The predictive life function often means the difference between a planned maintenance or costly unscheduled stoppage.