maxon motor
4-Q-EC Servoamplifier DES 70/10
Operating Instructions
5.4 Current
limit
Brushless maxon EC motors are particularly well suited for use in servodrives.
Very fast acceleration times and thermal overload protection are required.
The digital servoamplifier DES 70/10 operates with I
max
- and I
cont
-current limita-
tion, which satisfies both requirements.
Maximum output current I
max
< 30 A
Continuous output current I
cont
< 10 A
Ratio I
max
: I
cont
3:1
The continuous output current Icont (0 ... 10 A), adjusted with the potentiometer,
is available on an unlimited basis.
A higher current is also permitted for a short time (Imax = 3 • Icont), whereby
the length of time is dependent on the previous history of the current path.
Example 1:
a)
b)
During the time t
a
1
a higher current is permitted for motor acceleration. The cur-
rent is then limited to the continuous output current I
cont
.
If the motor is operated long-term with the continuous output current I
cont
, no
higher current is permitted (thus t
a
= 0 s).
Example 2: (cyclical mode)
a)
b)
In cyclical mode, the max. output current I
max
is available after a break of
approx. 10 s, provided that the current between the acceleration processes is
zero, otherwise time t
a
is reduced.
1
The length of time depends on the current value and the motor’s previous current load.
14
maxon motor control
April 2006 Edition / Subject to change
