National Research Council of Canada. NRC Institute for Ocean Technology
Text, Technical Report
Isolation Amplifier (Iso Amp)
During this work-term I modified and fixed an existing isolation amplifier. As well I integrated it into an Aerotech motor controller package by rewiring the back panel. Then I proceeded to make a duplicate isolation amplifier so that it could be interchangeable with the first. Once complete I tested the system under a variety of conditions in different places to compare it to a second (unmodified) Aerotech motor controller package. In doing so I found many flaws with the testing setup and how it should be configured, which is included in the report. The reason to make an isolation amplifier is to eliminate "ground loop" noise in the analog rpm and current data, which is being derived from the motor controller system and recorded on the Data Collection System. By utilizing an Isolation Amplifier to interrupt the ground path, which occurs by connecting the Motor Controller analog output data directly to the Data Acquisition System ground loop, noise is eliminated. The isolation amplifier makes use of the AD210, a wide bandwidth 3 — port isolation amplifier. This chip uses transformer coupling to separate grounds. Therefore the data you receive is actually your true signal. When modifying the isolation amplifier it helps to use the accompanying diagrams, schematics, and tables. In fact it is impossible to understand the circuit without them. When modifications are completed you can start the testing which is straightforward with the instructions. These tests just verify if the isolation amp is wired properly and acting the way it should. The next set of tests verifies that the motor controller system is operating correctly. The pictures and diagrams should be an aid to anyone setting up another data acquisition system as well.
National Research Council of Canada. Institute for Ocean Technology
St. John's, Newfoundland, Canada
Laboratory Memorandum (Institute for Ocean Technology (Canada)), no. LM-2004-28 (2004).