Motor motor winding dc resistance is one of the most important effect, the determination of the parameters is an important content of motor experiment. Through analysis of the measured resistance value, can preliminarily determine the subjects of the motor winding circle number, wire diameter, and around the root number, whether the connection methods and quality has reached the requirement of planning or expect and stators with any serious problem of short circuit between coils and so on. Group of the dc resistance and loss calculation and temperature rise calculation required parameters. So, experiment of the determination of winding dc resistance must pick a high precision instrument, and do it seriously, carefully, to make the test data with high accuracy. Measurement of winding dc resistance in motor experiments, dc resistance measurement instrument is generally selected direct acquisition value; Also can choose voltmeter and ammeter acquisition at the same time after the end of the winding dc current and winding voltage, using ohm's law and the winding dc resistance being measured, the way short name & other; Throughout the voltage & current method; 。 Ms。 And today's simple problems in the testing process for a brief summary to share with you. 1 dc resistance measurement instrument of the commonly used types of low dc resistance bridge is the most commonly used instrument measurement of motor winding dc resistance dc resistance bridge. Commonly used dc resistance of the bridge has two kinds, one kind is called a wheatstone bridge, also known as the wheatstone bridge. Another kind is called double bridge, also known as the kelvin bridge. Here & other; Arm & throughout; Refers to the attachment, measured resistance bridge with single arm is a wired each end; Arms is each side two attachment. 1 & Omega wheatstone bridge is used to measure; The resistance of the above; Double bridge is used to measure 1 & Omega; And the following resistance; Double bridge and compared wheatstone bridge, its advantage is to basically eliminate lead wire resistance produced by mistake. 'Digital electronic type dc resistance measurement instrument digital electronic type dc resistance measurement instrument is commonly used, its appearance standards. The working principle of this table only based on the above & other; Throughout the voltage & current method; 。 Compared and dc resistance bridge, it has the advantage of convenient use, easy reading, in a certain range of measurement, but also has the advantages of high precision; Lack of is, relatively poor stability. Should pay attention to when using this table only for winding don't exceed winding into the current 10% of the rated current, and the current time should be as short as possible, so as to avoid winding fever affect measurement accuracy. 2 dc bridge using process often make fault (1)Using wheatstone bridge measurement of small resistance, because the accuracy can not meet the requirements, lead to measurement accuracy, resistance uneven issue could not be found. This kind of problem in repair motor manufacturers often happen. (2)Power battery are lacking, bridge stability owe good, measurement data when small, simple measurement of imbalance. (3)Whose hands limit, gear selection is not reasonable, leading to a simple bridge burn out. (4)Failed to closed the power, because the measurement end contact, cause instantaneous loss battery. (5)When a phase of the motor when the head and tail, cannot choose bridge, found that only in the later inspection found during the test.
