KEB COMBIVERT F5-A Applications Manual page 281

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Adaption of special encoder
The maximum value for the number of increments per revolution of an encoder that can be entered in
Ec.01 or Ec.11 is 65535. The permissible maximum number of increments per revolution may be smaller
(for Sin/Cos encoders, e.g., 2048), depending on the interface type. By using the gear factor, encoders
with more increments per revolution can be used (see below: example 2). This adaption is not always
feasible and introduces limitations (e.g., no approach to reference point in response to the encoder-zero
impulse possible).
The main uses of the gear factor occur in the operating modes positioning and synchronous running. The effect
of the gear factor and the correct settings for the various mechanical set-ups are described in more detail in
chapters 7.12.3.4 and 7.12.4.4.2 .
Examples for the special case of encoder adaption via the gear factor are listed below:
Example 1: 3, pole-pair resolver on channel 1
Pole-pair number of the resolver = 3, pole-pair number of the synchronous motor = 3
ratio gear factor denominator to gear factor numerator must be equal to the pole-pair number
Ec.05 Gear 1 denominator = 3000
Ec.04 Gear 1 numerator = 1000
Ec.39 Encoder 1 over transmission = 1
Parameter Ec.39 must be set to: „1: motor encoder" for the operation of encoders that are not directly attached
at the motor or for the operation of resolvers with a pole-pair number > 1.
The gear factor is 1/3, the pole-pair number of the motor = 3
Gear factor x pole-pair number of the motor = 1
=> Synchronous motor can be operated in this set-up.
Example 2: Use of an encoder with too many increments per revolution
Encoder channel 1 is connected to a Sin/Cos encoder with 45000 increments.
The maximum value for Ec.01 for this interface type is 2048.
The increments per revolution are therefore split into 45000 = 1800 x 25.
The value 1800 is set as increments per revolution, the value 25 is set as gear factor.
Ec.01 Encoder (inc/r) 1 = 1800
Ec.04 Gear 1 numerator = 1 (must contain value 1)
Ec.05 Gear 1 denominator = 25
Ec.39 Encoder 1 over transmission = „2: Ec.1 x E. 5 (1 zero impulse per revolution)"
Ec.39 must be set to 2 for this special operation (splitting the real increments per revolution into gear factor
denominator and increments per revolution).
This special operation is only available for channel 1.
© KEB, 2012-10 COMBIVERT F5-A, -E, -H
Speed measurement
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