22 Mini Maestro User Guide
www.controltechniques.com Issue Number: 5
The following equation can be used to calculate a value for the RAI resistor:
Where:
Ip = Peak output current
Ratot = Ra + Rsp1 + Rsp2
Ra = Armature resistance (Ω)
Rsp = Brush resistance (Ω)
An approximate value may be found experimentally using a RAI resistor value of 400kΩ
to 600kΩ.
Adjusting the peak current
RIP resistor
When a RIN resistor is fitted, I
PEAK
may become excessively high in relation to I
NOM
. To
reduce the value of the peak current, use a RIP resistor.
Use the following equation to calculate the value of the RIP resistor:
Where:
I
LIM
= the new value required for I
PEAK
The following table may be used for finding an approximate value for I
PEAK
RAI 80 Vm×
Ke
motor
Ip
----------------------
× Ratot×=
Too low a value for the RAI resistor may modify the velocity loop response.
For guidance, contact Control Techniques.
NOTE
The new value for I
PEAK
must be ignored when the value of RIN is calculated.
NOTE
RIP
10 I
LIM
×()
I
PEAK
I
LIM
–()
------------------------------------
kΩ=
When the peak current is reduced, the ratio between I
PEAK
and I
NOM
is altered. This
alteration increases the time before I
2
t protection takes place.
In this case, the peak current is supplied for more than 2 seconds
NOTE
Model Current
3 / 6 5.8 5.6 5.4 5.1 4.9 4.1
3.9 3.6 3.0
7 / 14 13.5 13.0 12.5 12.0 11.5 10.0 9.6 9.0 8.4 7.0
10 / 20 19.3 18.6 17.9 17.0 16.5 15.4 13.7 18.9 12.0 10.0
14 / 28 27 26 25 24 23 21 19 18 17 14
Value KΩ 270 130 83 56 47 33 22 18 15 10
To Next Page
Loading...
