ENGINEERING INSIGHT
 |
Laser Doppler systems from Moor Instruments that are used for
measuring blood flow consist of an imaging system, a computer, and a power supply on a portable trolley.
|
Laser Doppler technology is used to measure microvascular blood flow in a number of medical diagnostic and clinical research applications. Bringing this advanced technology to the patient, however, requires a decidedly low-tech trolley. When Moor Instruments (Millwey, Axminster, UK) decided to introduce a new line of laser Doppler systems, it replaced the custom trolley it had been using with a more compact model that is commercially available. The change in trolley also precipitated a change in the power supply. After some searching, Moor Instruments sourced a transformer at REO Ltd. (Craven Arms, Shropshire, UK) that met its dimensional and operating performance requirements.
The laser Doppler systems from Moor Instruments consist of an arm-mounted imaging system and either an industrial PC or laptop computer. Power for the equipment is supplied via an isolation transformer that must comply with EN 60601 Parts 1-1-2 and 1-1/A2 regulations for electromagnetic compatibility and general safety, respectively. The transformer also must conform to UL and other international norms for use in the United States, Canada, and South America.
A Sleeker Trolley
The two new systems, the moorDLS and moorFLPI, use a commercially available trolley that is easier to manoeuvre and more compact and visually pleasing than previous custom-built models. “We wanted to use a smaller, more convenient trolley that would allow us to integrate the imagers, touch screen PC, and printers in one unit,” says Peter Jady, marketing manager at Moor Instruments. However, the trolley did not come equipped with a power supply. To complete the unit, the company needed to find an off-the-shelf, compact transformer that met the required medical standards and could be used worldwide.
 |
The Reomed isolation transformer from REO Ltd. features a toroidal-core construction.
|
The self-contained, fully enclosed transformer from REO Ltd. offers several benefits, according to Martin Potter, development engineer at Moor Instruments. “It fits neatly into the base of the trolley. Unlike the previous transformer, the Reomed requires no special wiring, which in turn ensures product consistency and reliability,” says Potter. “It is also available in different voltages in the same-size enclosure, so the trolley does not need to be modified for use in overseas markets.” The transformer can also be used for desktop applications and features multiple IEC socket outlets, enough for standard applications with sufficient capacity for adding customer-specific peripherals such as external hard drives and printers.
The transformer’s compact design is a by-product of the toroidal core’s construction. The core is made using electrical-grade steel strip, with a screen winding and tape isolation between the primary and secondary windings. It is virtually air-gap free and has very low losses. A plastic housing adds external protection and mechanical durability to the core. The whole transformer—fuses, input and output sockets, and mains switch—is housed within a metal enclosure designed for benchtop mounting.
Isolation transformers help reduce electric shock hazards and limit the risk of interference generated on the mains distribution network. REO’s Reomed transformer features low leakage current, high dielectric strength, low electromagnetic stray fields, and a very low value of primary to secondary capacitance. The transformer also protects essential electrical equipment connected to the secondary side. The unit achieves dielectric strength of Ž4 kV for reinforced and double insulation, as well as general earth leakage current of <500 µA. REO’s MDD-compliant range currently covers standard units for 115 or 230 V with power ratings of 300, 600, and 1000 VA.
To learn more about REO Ltd., select #9 on the reader service card or go to RequestLink at www.devicelink.com/emdm.
