Resolver Troubleshooting - Baldor 23H Series Installation & Operating Manual

Section 1
General Information

Resolver Troubleshooting

SYMPTOM
Continuous Overspeed Fault displayed on
keypad.
Intermittent Overspeed Fault displayed on
keypad.
When commanded to run, the motor will
not rotate and the keypad current display
is in excess of the motor rated amps.
Resolver coupling has failed.
The fourth auto–tuning step (Resolver Align) can be used to effectively troubleshoot the system. The
purpose of the test procedure is to adjust the electrical alignment of the resolver with respect to the motor
stator. There are four steps that the auto tuning procedure performs:
1
.
HELPFUL HINT: If the resolver speed (or poles) is unknown, a simple test can be useful to determine the
number of resolver speed. Temporarily set the resolver speed parameter to 10. With the resolver wired to
the motor control, apply power to the motor control. Go to the diagnostic menu and select the position
display. Rotate the motor shaft by hand until the display indicates approximately 0000:0000. Rotate the
motor shaft by hand exactly 1 revolution. If the keypad display shows approximately 4096, the resolver is
a 1 speed resolver, approximately 8,192 = 2 speed, approximately 12,288 = 3 speed and 16,192 = 4
speed, etc. in multiples of 4096. When the resolver speed is known, set the resolver speed parameter to
the proper number before starting the auto–tune test.
2.
3.
HELPFUL HINT: If the motor poles are unknown, this test can be useful to determine the number of motor
poles. A 2 pole motor will mechanically rotate the motor shaft 360°, a 4 pole motor will rotate 180°, a 6
pole motor will rotate 120°, a 8 pole motor will rotate 90°. Observing the mechanical rotation will indicate
the number of motor poles.
4.
MN723
Resolver wiring connection is
disconnected, a wire broken or miswired.
Missing or miswired shield.
Resolver wiring connection is intermittent.
Missing or miswired shield.
Resolver signal is outside of specification.
The resolver has failed or is not connected
properly. Resolver is not aligned properly.
This test initially displays the calculated number of counts per motor pole pair. For example, if using a
BSM4F motor, with the MOTOR POLES parameter set to 8 and a standard 1 speed resolver, the initial
keypad display will be 1024. The equation is: [4096 counts / (8 motor poles/2) = 1024].
The control then locks the motor rotor into a reference position using 50% of motor rated current
and then proceeds to check and re–adjust if necessary, the factory setting of the resolver
alignment parameter. This is similar to setting a clock to the local time. This parameter is
scaled in degrees.
From the reference position, the control slowly rotates the motor through a 360° electrical cycle
of current using 50% motor rated current. The number of counts from the resolver is compared
against the number calculated in step 1. From the above example with the BSM4F motor, if the
control receives approximately 1024 counts (
This portion of the test will take approximately 6 to 12 seconds.
As part of step 3, the resolver rotation is determined and the feedback alignment parameter is
adjusted to the appropriate direction, FWD or REV.
POSSIBLE CAUSE
±10%
) from the resolver, then the test will pass.
CORRECTIVE ACTION
Inspect and repair the resolver wiring.
Terminate shield properly @ J1–28
Inspect and repair the resolver wiring.
Terminate shield properly @ J1–28.
The resolver output Sine and Cosine
maximum voltage must be 2VAC RMS
±10% at the J1 terminal strip. This high
frequency voltage (5kHz) can only be
measured with a Fluke 87 or equivalent
meter or an oscilloscope. Rotate the
resolver to find the max voltage.
Verify the resolver is connected and wired
properly.
Disable control and rotate motor by hand.
If the position display in the keypad
diagnostic menu shows a position change,
then the resolver is probably working.
Run the auto tune test to align the resolver.
Replace resolver coupling.
Troubleshooting 5-5