Continental Hydraulics Installation Manual
Page 24 of 24
CEM-PA-B
CHI 1020688 01/2016
FAULT
CAUSE / SOLUTION
ENABLE and START
(PIN 6) are active, the
READY LED is active,
the pressure control
loop works, but the
pressure is oscillating or
the pressure UP and
DOWN time is too slow.
The capability of the hydraulic system has to be checked. Deactivate PIN 6 for
open loop control and check the pressure build up and down time. If the system
is in open loop still unstable, check the hydraulic and the dither/ PWM setup
first.
1. Check the parameters C:I, C:P and C:SC.The parameter C:SC has the
following relevance:
With this parameter you can increase or decrease the feed forward gain to
the valve. C:SC 8000 (80 %) means, the remaining 20 % must be provided
by the PID compensator. The integrator limitation should be set to 2500...
3500 (25 % ... 35 %)
8
.
2. The C:P (P-gain) is to increase in steps
9
to the point where the pressure is
going to be u
nstable. At this point, C:P should be decreased for 30… 50 % to
get an effectual stability margin.
3. The integrator time constant C:I fixes the static error. Typical values are:
100 ms to 1200 ms. Optimize this parameter by monitoring the transient
response.
ENABLE and START
(PIN6) are active, the
READY LED is active,
and the pressure control
loop works, but there
are high errors mainly at
lower or higher
command pressure.
The non-linearity of the valve is higher than the controlling range of the
integrator. The parameter LIM:I should be increased.
ENABLE and START
(PIN 6) are active, the
READY LED is active,
and the pressure control
loop works. Lower
pressure at the
beginning causes that
the system is not
actuated and that no
pressure build-up
occurs.
In this case, the integrator threshold (activation point of the integrator) in
combination with the controller setting is too high. The parameter LIM: S should
be reduced.
8
The limit value should be higher than the remaining control range (100 % - C:SC), additionally you have to
add a value to compensate the non-linearity of the valve.
9
Optimizing in steps is a general description. Our experience: you can change the parameters in steps from
+20 % or rather -20 % for a rough adjustment of the actual value. For a fine adjustment you can select
smaller steps.
