9
ANTRIEBSTECHNIK
6
10
9
KEB COMBIVERT F4-C
Name: Basis
19.11.98
6
Section
Page
Date
©
KEB Antriebstechnik, 1997
All Rights reserved
Chapter
Functional Description
Encoder Interface
Tacho generators supply an analog signal which is proportional to the speed of the
tacho generators. The direction of rotation is gained from the sign of the analog signal.
The analog signal of the tacho generator is converted into a +/-10V signal in the
evaluating circuit. By way of a potentiometer the tacho voltage at maximum speed
can be adjusted to 10 V (refer to „Adjustment of Tacho Generator“). The ±10V signal
is fed to the analog option channel of the control card (see Chapter 6.2 „Analog In-/
Outputs“).
The conversion into speed is based on following formula:
n
dr
=
.44
100%
1.
Determine the maximum speed of the motor in the application (nmax_Motor)
Determine the speed of the tacho at maximum motor speed (nmax_Tacho)
Determine tacho voltage at nmax_Tacho (Umax_Tacho)
In case of Umax_Tacho > 100V use another tacho or reduce maximum tacho
speed!
2.
Adjust analog amplifier for the optional analog input:
Indication of analog values after amplification:
Adjust An.22 bit 7
Amplification to 1:
An.23 = 1
Offset x to 0:
An.24 = 0
Offset y to 0:
An.25 = 0
Noise filter analog option
An.26 = 1…4
Zero clamp speed analog option
An.27 = 0…11
Adjust reference speed to maximum tacho speed:
dr.44 = nmax_Tacho
Adjust encoder interface selection: (channel 2= Tacho):
dr.24 = 2 oder 3
Adjust gearbox factor for channel 2:
dr.36 = nmax_Motor / nmax_Tacho
Adjust source of actual speed display on channel 2:
cn.3 = 2
Adjust motor data (important are rated motor speed and rated motor frequency).
3.
Accelerate motor in idle operation to maximum speed and operate with constant
speed.
Adjust potentiometer on the interface card up to ru.45 = 100%.
If 100 % are not attained, even if the potentiometer is turned to the limit stop,
increase An.23 up to ru.45 = 100%.
ru.1 now indicates the actual motor speed.
Under consideration of the resolution of parameter dr.37 or dr.38 it results in following
formula for Delta n in 1/min:
[
]
∆
n
dr
dr
1
3750
25 2
37
/ min
.
*
.
=
This shows, when using encoders with low no. of increments only a rough speed
resolution can be attained or the time gate must be chosen very large which results
in a slower detection.
By way of parameter dr.29 (channel 1) or dr.34 (channel 2) the direction of rotation of
the speed measurement may be reversed.
6.10.8 Evaluation of
Tacho Generators
Adjsutment of tacho generator
