NOVUS Controller N120 - Manual (Page 3)

NOVUS AUTOMATION 3/14
• lo – Alarm of Absolute Minimum Value
It is activated when the measured value is below the value defined in
the alarm Setpoint.
• ki – Alarm of Absolute Maximum Value
It is activated when the measured value is above the value defined in
the alarm Setpoint.
• dif – Alarm of Differential Value
In this function, the parameters “SPA1”, “SPA2”,”SPA3” and “SPA4”
represent the PV deviation as compared to the main SP.
Using the Alarm 1 as example: for Positive SPA1 values, the
differential alarm will be triggered when the PV value is out of the
range defined in:
(SP –SPA1) to (SP + SPA1)
For a negative SPA1 value, the differential alarm will be triggered
when the PV value is within the range defined above
• difl – Alarm of Minimum Differential Value
It is activated when the PV value is below the value defined in:
(SP –SPA1)
Using the Alarm 1 as example.
• difk – Alarm of Maximum Differential Value
It is activated when the PV value is above the value defined in:
(SP + SPA1)
Using the Alarm 1 as example.
The alarm functions are described in Table 5.
SCREEN TYPE ACTUATION
Off Inoperative Output is not used as alarm.
Ierr Open sensor
(input Error)
Activated when the input signal of PV is
interrupted, out of the range limits or
Pt100 in short-circuit.
Rs Event (ramp and
Soak)
Activated in a specific segment of
program.
Lo Minimum value
(Low)
SPAn
PV
Ki Maximum value
(High)
SPAn
PV
Dif Differential
(diFerential)
SV
PV
SV + SPAn SV - SPAn SV
PV
SV - SPAn SV + SPAn
Positive SPAn Negative SPAn
Difl Minimum
Differential
(diFerential Low)
Positive SPAn Negative SPAn
SV
PV
SV - SPAn SV
PV
SV - SPAn
Difk Maximum
differential
(diFerential High)
SV
PV
SV + SPAn SV
PV
SV + SPAn
Positive SPAn Negative SPAn
Table 5 – Alarm Functions
Where SPAn refers to Setpoints of Alarm “SPA1”, “SPA2”, “SPA3”
and “SPA4”.
ALARM TIMER MODES
The controller alarms can be configured to perform 3 timer modes:
• One pulse with defined duration;
• Delayed activation;
• Repetitive pulses;
The illustrations in Table 6 show the behavior of the alarm output for
various combinations of times t1 and t2. The timer functions can be
configured in parameters A1t1, A1t2, A2t1, A2t2, A3t1, A3t2,
A4t1
and A4t2.
OPERATION T 1 T 2 ACTION
Normal
Operation
0 0
Alarm Event
Alarm
Output
Activation for a
defined time
1
to
6500 s
0
Alarm Event
Alarm
Output T1
Activation with
delay
0
1
to
6500 s Alarm Event
Alarm
Output T2
Intermittent
Activation
1
to
6500 s
1
to
6500 s Alarm Event
Alarm
Output T1 T2 T1
Table 6 – Temporization Functions for the Alarms
The signs associated to the alarms will light when the alarm condition
is recognized, not following the actual state of the output, which may
be temporarily OFF because of the temporization.
INITIAL BLOCKING OF ALARM
The initial blocking option inhibits the alarm from being recognized if
an alarm condition is present when the controller is first energized (or
after a transition from run YES NO). The alarm will be enabled only
after the occurrence of a non alarm condition followed by a new
occurrence for the alarm.
The initial blocking is useful, for instance, when one of the alarms is
configured as a minimum value alarm, causing the activation of the
alarm soon upon the process start-up, an occurrence that may be
undesirable.
The initial blocking is disabled for the sensor break alarm function.
SOFT-START
The soft-start feature avoids abrupt variations in the power delivered
to the load regardless of the system power demand. .
This is accomplished by defining a limiting ramp for the control
output. The output is allowed to reach maximum value (100 %) only
after the time programmed in the soft-start parameter has elapsed.
The Soft-start function is generally used in processes that require
slow start-up, where the instantaneous application of 100% of the
available power to the load may cause damages to parts of the
system.
In order to disable this function, the soft-start parameter must be
configured with 0 (zero). Soft Start is available only for Control Output 1.
CONTROL MODE
The controller can operate in two different manners: Automatic mode
or Manual mode. In automatic mode the controller defines the amount
of power to be applied on the process, based on defined parameters
(SP, PID, etc.).
In the manual mode the user himself defines this amount of power.
The parameter “ (trl ” defines the control mode to be adopted.
PID AUTOMATIC MODE
For the Automatic mode, there are two different strategies of control:
PID control and ON/OFF control 1.
PID control has its action based on a control algorithm that takes into
account the deviation of PV with respect to SP, the rate of change of
PV and the steady state error.
On the other hand, the ON/OFF control (obtained when Pb=0)
operates with 0% or 100% of power, when PV deviates from SP.
The determination of the PID parameters (Pb, Ir and Dt) is described
in the item DETERMINATION OF PID PARAMETERS of this manual.
CONTROL 2
The N120 offers a second independent control output (Control Output
2). This output, with only proportional action is generally used in
cooling processes when using the heating action the control output 1.