How to determine the first and last ends of a motor using only a multimeter
General three-phase power motors, regardless of the old and new, wired out of the first end of the tail end of the sub-package, and the line colour with the same phase of unity, unnecessarily special distinction, but there are always exceptions, as an electrician, if you encounter a line colour is not unity, the head and tail is also confusing, pick up the line is indeed a relatively troublesome thing, especially not encountered this situation electricians, it is easy to a moment at a loss, without a clue.
Today to talk briefly about how to use a multimeter to find out how to use this situation step by step to find the first end of the end, and then set a good mark, which is actually one of the necessary skills as an electrician.
The first step, with the multimeter's resistance file of the motor's seven wires into three groups, a group of ground, which is the easiest to determine, the other two groups, regardless of the first and last, as long as the conduction of the separation of the two groups on the line, the same group must not be connected to the phase, there are motors have a thermal protection line, which is generally very thin wire are obviously very intuitive, you can distinguish between the outside directly.
The second step, the three groups of good marking, because the ground line is marked separately, do not care about it, the main task is how to distinguish between the two groups of line ends out of the first or the end. First of all, a group of three wires marked 1'2'3, the other group marked 4'5'6, with a multimeter with the minimum current gear were in contact with the two groups of line end, pay attention to be sure to contact in place, to prevent contact is not in place to cause measurement errors, to ensure that the contact is in place, the hand rotating the motor, if the dial on the number of displays, sensing the current, then the two groups of line end of the end of the first and the end of the end of the same end (https://) then switch the motor to a different end of the first and the end of the line. (www.diangongwugwu.com/独家原创 All rights reserved) then switch the 1'4 end, become 2'3'4 and 1'5'6 two groups, repeat the above action procedures, use this method and so on, until the dial does not respond to the rotation of the motor, sensing the current, indicating that the first and last end has been successfully differentiated into two, so that up to three times, can be differentiated. Successful.
This distinction between the first and the end of the method, because again with the pen to contact the two groups of line end, but also to turn the motor, a person operating up to feel the hand is not enough, here I tell you a small method, can be very easy to operate, is the method shown in the picture, with a circuit breaker switch, the meter needle and the line end are fixed, so as to ensure that the contact is in place, and liberate both hands, you can free up your hands to easily rotate the motor, the operation is much easier, especially in the case of the first and the end of the motor. It is much easier to operate, especially if there is no one to assist, so it is very convenient.
In addition, this method, whether it is a digital meter or pointer meter are universal, as long as you master the method, step by step, for determining the end of the first and last is not difficult. Find a pointer multimeter (digital table can also be, but the number of big jumps, pay attention to the amount of change), first with the resistance gear, the three groups of windings to find out, this is easy, right, direct measurement of the pass can be, there is certainly a group of resistance, infinity is another group.
Then use the AC milliamps to distinguish a winding in the first and last end, the essence is the same name end confirmation. According to the motor design, according to the following figure to wiring, if the first and last wiring right, rotating, a little residual magnetism, rotating it will send a little electricity, this time the three-phase is balanced, so the multimeter is equivalent to the zero line, there should not be current through.
