SECTION 10: TROUBLE-SHOOTING GUIDE T200 User's Manual
PAGE 10-29
10.6.4 Problem: Excessive Audible Noise from the Motor
The motor movement is somewhat acceptable, but there is unacceptable high frequency noise from the motor.
Table 28: Causes of Noise in the Motor
Cause Check/[Correction]
Control Loop
Gains are too
High
Retune the velocity and position loop gains, so that these are lower in value to reduce the effects
of noise. [The P and I gains need to be set at lower values which are still appropriate for the load
(see Section 6.6.2, Velocity Loop Tuning). The G gain may need to be reduced (see Section 6.6.3,
Position Loop Tuning).
Excessive
Noise Pickup
on the
Resolver
Position
Sensor Cable
Low noise content on the resolver position feedback signals is critical for good servo-
performance. Check the display of velocity on an analogue test point TP2 or using the WinDrive
data-logger. Note that about 10RPM of noise is normal because of Analogue to Digital conversion
accuracy and other quantisation effects. [Check the following:
[Ensure that all resolver cable wires are properly connected at J6 of the T200. (see Section
3.14 for pinouts).
Ensure that the resolver cable shield is connected at both the motor to Protective Earth and
the T200 end to the chassis via a J6 as detailed in Section 3.14.
If the resolver cable run from the motor is alongside the motor power cable, try to separate
the cable runs wherever possible.]
T200 Chassis
is not well
earthed
Ensure that the connection between the T200 Chassis and Protective Earth is as low resistance
(and impedance) as possible.
[Use a braided wire, or low AWG wire to connect the T200 chassis to Earth. A PE connection
point is provided at the top right hand side of the T200's front panel (see Section 3.4 for a diagram
of the Front Panel) to augment the TB2 PE connection point.
Alternatively use a high conductivity common metal mounting panel for all T200's, so that there is
a good low impedance conduction path for high frequency noise away to Protection Earth. For
best results resistance should be less than 0.1Ohms to Protective Earth from the T200 chassis.]
Motor Body is
not well
earthed
High frequency currents flow in the motor internal windings. The motor body should be
connected to a metallic path to Protective Earth, to conduct high frequency capacitively-coupled
noise generated in the motor, which would otherwise flow in motor power cables lines and
shields.
[Ensure that the motor has a low resistance path to Protective Earth, with the motor power cable
disconnected. For best results resistance should be less than 0.1Ohms to Protective Earth from the
motor's metallic body.]
Motor Power
Cable shield
not well
Terminated
For best noise shielding results, the motor cable shield should be connected at BOTH ends of the
cable (to the T200 chassis through the PE connection or through the EMC bracket as shown in
Section 3.14.5, and to the motor body at the motor end).
If the motor shield cannot be connected at the motor end, then the EMC bracket should be used, as
shown in Section 3.14.5 and 3.14.6.
Damaged
Motor
Bearings
Remove all power from the T200. If possible remove the motor from the machine and check the
motor can rotate freely by hand, if the motor does not have a brake. Check if there is radial play in
the motor shaft with respect to the motor housing.
[Return the motor to Moog for repair.]
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