OHAUS FD SERIES Service Manual

Also see for FD Series: Instruction manual User guide Quick start guide

Contents

OHAUS FD SERIES Service Manual Manual pdf 24 page image

3-8CHAPTER 3 SCALE TESTING AND CALIBRATION3.6 PERFORMANCE TESTS3.6.1 Segment Display TestConnect the AC Adapter into a suitable power source and connect it to the scale. Turn the scale on, allsegments are enabled and displayed briefly followed by a software revision number. This is a segmentdisplay test. Figure 3-3 is a full display test.√∑ [x -x ]2n - 1σFigure 3-3. Segment Display.Accurate performance of the FD Series Scales is determined by a series of three performance tests,Repeatability Test, Off-Center Load Test and Linearity Test. These tests are used to evaluate the scaleperformance before and after repairs. Each scale tested must meet the requirements specified in each testas well as the specifications listed in Tables 3-2 and 3-3. A scale passing each of these three testscomplies with Ohaus specifications.3.6.2 Repeatability TestRepeatability is the standard deviation of a set of similar weight readings. To determine the repeatability,perform the following test:1. Zero the scale. The reading on the display should be 0kg.2. Select a test weight near the maximum capacity of the scale and place it on the center of thepan. Observe and record the reading.3. Remove the test weight. The reading should return to 0g.4. Repeat this test for ten readings. Calculate the standard deviation of the ten load readingsusing a calculator with statistical capabilities or use the following formula:Standard DeviationStandard DeviationStandard DeviationStandard DeviationStandard Deviation ( )=x = weight reading in kgx = Mean (average) of 10 readingsn = number of readingsA worksheet has been provided for entering the data and calculation results for the Standard Deviation(Figure 3-4). Step by step instructions for calculating the standard deviation are provided in Figure3-5 and a sample calculation is provided in Figure 3-6.