De-Excitation (Shutdown) Contact: Instructions - MarelliMotori MEC-100 Manuel De L'utilisateur

Controller
Increase of K
P
Increase of K
I
Increase of K
D
It is to be specified that the above-mentioned relationships are not accurate, since controllers depend each other, but they can
be considered enough to tune controllers in order to obtain the best possible transient response. Generally speaking, the
Proportional controller (K
P
readiness) and decrease, but not to eliminate, the steady-state error. The Integral controller (I controller with K
eliminates the steady-state error but worsens the transient response (reduces the stability). The Derivative controller (K
increases the stability of the system, by improving the transient response.
3.11.2. Derivative Adjustments
The MEC-100 Interface System provides two further adjustment parameters (for derivative adjustments) to improve the transient
response:
• –
st
1 Derivative Item
calculation.
• –
nd
2 Derivative item Filter: describes the time constant, referred to the discrete time, of the low-pass filter used to eliminate
the derivate noise.
3.11.3. P.I.D. in PF/VAR Modes
The MEC-100 Interface System provides 3 P.I.D. controllers and 2 derivative adjustments to set the stability in AVR Mode. Only
P.I. controllers must be set in PF and VAR Modes. For the setting of each parameter, see Par. 5.7.5.

3.12. DE-EXCITATION (SHUTDOWN) CONTACT: INSTRUCTIONS

Most of the generator connection diagrams include a de-excitation (shutdown) contact between the generator power source
(main terminals, auxiliary winding, PMG, etc.) and the MEC-100 supply terminals P1-P2(-P3 if used), see Par. 4.4.
Switching-off the de-excitation contact leads to stop powering the generator exciter in a short time.
Especially in generator/hydro turbine applications, the load rejection (i.e. when generator is paralleled with the network) must be
always simultaneously accompanied by the prompt excitation shutdown of the generator, in order to limit the generator over-
voltage due to the load rejection and the turbine over-speed.
In case of hydro turbine applications, the de-excitation contact must be always switched-off simultaneously
with the load rejection and/or disconnection from parallel operation.
Generally, Marelli Motori recommends to associate the momentary switch-on of the STOP contact (C2) to the switch-off of the
de-excitation contact. This procedure permits to accelerate the excitation shutdown and strongly limit the generator over-
voltage.
WARNING: during the parallel operations, STOP contact and/or de-excitation contact can be only used
simultaneously with the load rejection and/or disconnection from parallel operation.
WARNING: read carefully all the instructions about START and STOP contacts operating use, see Par. 3.5.
WARNING: Marelli Motori recommends to associate STOP contact to the de-excitation contact only for
improving the generator transient performance during the load rejection and/or disconnection from parallel
operation, and safe the MEC-100 regulation system.
963857137_M
Ramp-up Time
Decreases
Decreases
Does not influence
) will contribute to reduce the step-response rise time (parameter which characterizes the response
Time: describes the number of sampling intervals, referred to the discrete time, used for the derivate
Overshoot Transient Length
Increases Does not influence
Increases Increases
Decreases Decreases
MEC-100 – Marelli Motori
Steady-State Error
Decreases
Eliminated
Does not influence
constant)
I
71
)
D