Proper Encoder Mounting Procedures; Encoder Mounting For Geared Applications; Encoder Mounting For Gearless Applications - O. Thompson Microflite Ultra 2000 Installation & Adjustment Manual

Sometimes referred to as:
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A is pronounced A not
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B is pronounced B not
Three twisted pairs, each with an overall shield is used to wire the encoder.
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A and A are wired with a single twisted pair with an overall shield wire.
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B and B are wired with a single twisted pair with an overall shield wire.
The +5 volts and Com to the encoder is wired with a single pair with an overall shield wire.
All the shield are connected together and terminated at the drive. There should be no connection
of the shield at the encoder end. Tape off or insulate the shield wires at the encoder end.
4.3

Proper Encoder Mounting Procedures

The most often overlooked item in drive applications is the proper mounting of the encoder. Poor
or improper mounting of the encoder leads to an unstable speed feedback signal to the drive.
Unstable feedback signals become amplified within the regulator circuits and lead to oscillations
and vibrations in the ride.
The most common misunderstanding is that the speed feedback signal should exactly reflect the
actions of the car. This is incorrect in that mechanical resonances and instabilities can exist in a
system that should not be incorporated into the motor control. An example of mechanical instability
would be improper gear lash in a geared application.
The speed feedback signal should exactly reflect the action or speed of the motor in all cases. The
encoder signal is also looked at in terms of resolution. An encoder with the proper PPR, or pulses
per revolution, should be selected. As a rule of thumb, if the encoder is mounted to the motor shaft
in a gearless installation, it should be roughly 10,000 PPR. If it is equipped with a wheel and
mounted to drive sheave, it should be either 2,500 or 5,000, depending on motor RPM. An
encoder driven of the motor or worm shaft should be 2,500 PPR.

4.3.1 Encoder Mounting for Geared Applications

WE RECOMMEND the encoder for geared applications be coupled directly to the motor or worm
shaft using an isolated flexible coupling supplied by the encoder manufacturer. The encoder shaft
should not be hard fixed to the motor shaft due to imperfections in the motor shaft alignment. If
the encoder shaft is hard coupled to the motor shaft without a flexible coupling, premature encoder
failure will occur.
WE DO NOT RECOMMEND driving the encoder from the drive sheave on geared applications.
This is primarily due to the mechanical inconsistencies in the gear box. These will be introduced
into the motor control circuits, and the electrical stability of the system will be compromised.

4.3.2 Encoder Mounting for Gearless Applications

Revision: AA 2.2
Microflite Ultra 2000
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A A B B
A A- B B-
Printed 03 - 15 - 03 4 - 6