Medical Equipment Compliance for Servo Drives From ADVANCED Motion Controls
By Robotics Trends Staff - Filed Nov 14, 2007

Photo Courtesy:  Advanced Motion Controls

Medical equipment manufacturers (OEM’s) producing technology for treatment, diagnostics or closely related support services are increasingly relying on motion control for precision movements. Inherently, drives and drive systems are required to meet stringent requirements that comply with regulations imposed by the FDA and FCC. These standards are beyond those set forth by UL and CE for general industrial equipment, which mainly focus on device safety compliance. In fact, FCC Class B compliance is more difficult to achieve when it comes to levels of EMI radiation allowed when compared to CE device certification.

Drives today are Pulse Width Modulation (PWM) switching power devices made to switch current on-and-off at relatively moderate frequencies at or above 20 KHz. These transitions create ‘noise signatures’ at much higher frequencies, typically 10’s of MHz to 1 GHz, and the proximity of other equipment in the general area can be adversely affected given their sensitivity. Therefore when used in medical equipment, servos are also required to be low noise devices. Engineers now have a choice and do not have to concern themselves too much with other system components for specialized grounding, shielding or encasing to meet these rigorous standards. A typical example includes an independent laboratory test indicating a -10 dB level from maximum allowable across 30 MHz to 1 GHz with the servo drive operating at 80 VDC and delivering up to 10 Amps.

ADVANCED Motion Controls’ servo drives can be built to these standards and employ the following design techniques: compact PCB integrated flat wire inductors for motor outputs and power inputs, common mode filtering on logic supply input, PCB inter- and intra-layer layout techniques including grounding of separate circuitry stages and decoupling capacitors at all interface points to the drive. These implementations eliminate the need for external considerations and reduces the overall integration of the servo drives into medical equipment.
For more information, contact Karl Meier, Marketing Manger, ADVANCED Motion Controls at (805) 389-1935 and reference: Medical Equipment Design Standards. For additional information regarding general products, visit our web site at http://www.a-m-c.com.

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