416 Electrical Systems indicators, two rotation indicators, and a test button. Sim- ply connect the three input leads to the three phase con- ductors. Th e voltage-present indicators verify that voltage is present in each phase. Th e phase relationship is indicated by one of the two rotation indicators. For phase sequence testing, some testers have a but- ton that must be pressed to read the rotation. Some high-end units have a motor rotation test capability to identify the proper sequence of the motor leads. For motor rotation testing, the tester has three input/ output jacks, a power indicator, two rotation indicators, and a test button. To test, connect the three motor leads to the three input/output jacks. Press and hold the test but- ton, and observe that the power indicator is illuminated. Looking at the shaft end of the motor, rotate the motor shaft and observe the rotation indicator. Verify that the rotation indicator shows the direction the motor is rotat- ing. Rotate the motor in the opposite direction and observe the direction of rotation indicator that is illuminated. If the rotation indication is opposite the direction the shaft is rotating, reverse any two of the three conductors. T E C H T I P Phase Sequence Tester Applications A phase sequence tester is an extremely useful tool when working with conveying systems, pumps, compressors, and other rotating machinery using three motors. 21.3.12 Infrared Thermometer An infrared (IR) thermometer, Figure 21-29, is a non- contact electronic device that measures infrared radia- tion emitted from a surface or object to determine its temperature. Th e infrared thermometer does not mea- sure the temperature of the air, only the matter it is aimed at. Most IR thermometers have an aiming laser to make it easy to determine the surface being measured. Th e area of measurement sensitivity is in the shape of a cone. Th e further the IR thermometer is from the surface being measured, the larger the area that is measured. Th e closer the IR thermometer is to the surface, the smaller the measured area. Most IR thermometers are marked with the distance vs area. Reproduced with permission, Fluke Corporation Figure 21-29. Infrared (IR) thermometers determine temperature by measuring the amount of infrared radiation emitted from an object. Th is device proves useful in measuring the tempera- ture of bearings to determine imminent failure. If the bearing on one end of a motor shaft is warmer than that on the other, watch out for a failure in the near future. High temperature of an electrical connection is a good indication that it is potentially loose and may soon fail. Transformer and motor temperatures may be checked to determine if they are within the manufacturer’s specifi - cations. Such devices may fail if they overheat. 21.4 CALIBRATION Calibration is an important part of test and measurement equipment maintenance. Test equipment should be cali- brated on a periodic basis to ensure its accuracy. Many companies are certifi ed to various quality standards, such as ISO 9001. Th ese quality system standards require that all test and measurement equipment be calibrated. Calibration involves verifying that the test or mea- surement device measures within the manufacturer’s specifi cations. Calibration does not necessarily mean that the test or measurement equipment must be cor- rected or recalibrated. Rather, the diff erence between the measurements the test equipment makes and the stan- dard it is compared against is known and documented. Diff erences outside the manufacturer’s specifi cations indicate that the equipment needs to be recalibrated and should not be used or relied upon. Some large companies have their own calibration laboratory. Others employ calibration fi rms. Most cali- bration can be done on-site, but specialized test equip- ment may need to be shipped to a calibration lab. Copyright Goodheart-Willcox Co., Inc.