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more non-linear the response becomes, see the red curves.
As an engineering rule of thumb “a” should be ≤0.1 to have an acceptably linear
response, although ≤0.2 is also often accepted.
The next consideration is the current that can be supplied by the 10V terminal. This
gives the minimum allowed potentiometer value. The lower the value is, the more
power is dissipated in the potentiometer, therefore you want to keep the potentiometer
resistance as high as possible.
Example for VFD-E:
- The AVI input resistance is 47kΩ.
- Select potentiometer ≤0.1*47k=4.7k.
- The 10V terminal can supply 3mA so the minimum potentiometer value is
10V/3mA=3.3kΩ.
- So in practice a potentiometer value between 3.3kΩ and 4.7kΩ gives a linear
response and will not overload the 10V terminal (if a≤0.2 is accepted, then a
potentiometer between 3.3kΩ and 10kΩ (=47kΩ/5) can be used).
Q Which parameters must be set when using the built-in brake chopper or a brake
unit?
A The OV stall prevention must be disabled because it would interfere with the brake
chopper action and the DC-bus voltage level at which the brake chopper is activated
must be set.
VFD-EL
VFD-E MS300 ME300 MH300 C2000
C2000
CFP2000
VFD-ED
Disable OV
stall
prevention
Pr06-00=0 Pr06-01=0 n.a.
n.a. Pr08-19 Pr07-00
Q How to connect a 4-20mA sensor to an analogue input?
A 4-20mA sensors have 2 terminals and “source” the current into the input. They need
normally a minimum voltage drop of ca. 8V
DC
.
On Delta drives the input impedance of 4-20mA inputs is 250Ω (please refer to the
user manual which input can be used for 4-20mA and how to set it).
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