Topic
HOW TO IDENTIFY LEADS
OF UNTAGGED MOTORS?
HOW CONNECT THE UNTAGGED 6-LEADS MOTOR
Trial and Error
Procedure:
• The easiest way to connect or determine and tag the leads
of the motor is by trial and error method.
• It is safer to connect it in Y-connection, then, jog the motor
if it will run normally. Measure the current if it is within the
normal range with respect to its rating.
• If it run normally, the leads connected to the source upon
testing could be tag as 1, 2 and 3. Then, their opposite ends
could be tag as 4, 5 and 6 respectively.
• If it doesn’t run normally and the current goes far beyond
the limit, try another combination until it runs normally.
Make it sure to jog the motor in shortest time as
possible to avoid overheating of winding.
HOW CONNECT THE UNTAGGED 6-LEADS MOTOR
Inductive Kick
Procedure:
• For large motors were heavy current will be drawn upon testing, the trial
and error method is dangerous to perform.
• The polarity of the winding can be determined by observing the
inductive kick when a small DC current is introduced into it, then
suddenly removed.
• Connect the windings in Y-connection, then, momentarily inject the
current into one winding then observe the induced voltage on the other
winding. It can be a negative or a positive going voltage.
• The result must be true for all phases tested. If not, try another
connection until this hypothesis is attained.
• If the said condition is true for testing of all winding, the outer leads can
be tagged as 1, 2 and 3. The leads at Y-point can be tagged as 4, 5 and 6
respectively.
• See the particular set-up shown in the next figure.
Inductive Kick Test Set-Up
• If analog voltmeter is used, it shows downscale on the “make” then upscale on the
“break”.
• However, this test do not aim to determined the phase direction but only to
determine the beginning and ending of the winding.
Inductive Kick for 9-leads:
Test Set-up 1
• In 9-leads motor, winding that is opposite to the supplied
winding doesn’t produce inductive kick.
Inductive Kick for 9-leads:
Test Set-up 2
• If analog voltmeter is used, it shows down scale on the “make” then
upscale on the “break”.
• This set-up is almost the same for 6-leads, only we can’t access the mid-
point of star.
HOW CONNECT THE UNTAGGED 12-LEADS MOTOR
Procedure:
• By experience, trial-and-error and inductive kick method did not work for this
number of leads because there are several combination can be made for 12-
leads motor.
• However, if there are only few leads are untagged, trial-and-error or inductive
kick method would probably work.
• There is an accurate method in tracing the windings by magnetizing
individually the winding or may be a pair of windings ,then, detecting the
magnetic field by using a permanent magnet.
• However, in this method, the stator must be placed in vertical position without
a rotor.
• The magnitude of the current should be controlled just to let the magnet
detects the magnetic field produced by the supplied winding or a pair of
windings.
• This procedure is also applicable for 6-leads motors because they are basically
the same.
• Review on basic electrical principles.
Three Phase Sine Wave
Phase Angle
• The phase B is lagging from phase A by 120 elec. degrees.
• The phase C is lagging from phase B by 120 elec. degrees.
• Electrical degrees doesn’t always means the same from
geometrical degrees, it is based on changing the polarity of
voltage and/or current from positive to negative or vise versa.
• It takes 180 electrical degrees of changing from peak positive
to lowest negative and vise versa.
• In two pole machine, one revolution produce 360 elec.
degrees. This is exactly the same in geometric degrees.
• In four pole machine, one revolution produce 720 elec.
degrees. This is double for geometric degrees.
Magnet Mapping
• Supply a winding or a pair of windings with a 12 volt DC power
source in series with an adjustable power resistor. Control the
current just to create enough magnetic field to be detected by a
free hanging permanent magnet. By experiment, a radio battery
charger can be also used.
• Observe or change the polarity of the power supply so that the pair
of windings produce a north pole then south pole with respect to
clockwise direction. Just assign an arbitrary starting point.
• North pole field will be attracted with south pole of the hanging
permanent magnet.
• Locate the center of each winding and put a distinctive mark.
• Locate the 2nd half of the 1st selected phase using the same
procedure. For 6-leads motor all windings of one phase are mostly
connected in series.
Center points of winding
• Take note that the 2nd half of the 1st phase winding positioned
at exactly opposite location. When drawing lines connecting
their centers create a crossing perpendicular lines.
• Repeat the procedures until all centers are marked.
• Mark may be tag as 1(N), 1(S), 2(N)… and so on or any marks
that are convenient and comprehensive.
• In each mark the positive and negative leads must be also
mark. Ex. 1+ and 1-, then, 2+ and 2- and so on.
• Review on winding pattern.
3-PHASE, 4-POLE STATOR WINDING ORIENTATION
Scheme of Mapping
Polar Pattern of Center Points
Final Tagging
Tips on Hands-on
Note:
• You can see for your self how the permanent magnet reacts on the
energized coil.
• Never energized the winding for longer period, the power supply
could be damaged that way.
• Try to locate the centers by observing the movement of the
permanent magnet.
• We can just assume that the north pole of the permanent magnet
points the earth’s north pole as a compass do. Then, mark the poles
of the test magnet.
• In inductive kick procedures, you can only touch by your bare hand
only one point of the tested winding, because you might feel a
strong kick voltage once your skin complete the current path.
