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AUTO TUNING MODE :
To enter in this mode, Press and hold SHIFT key for minimum 3 sec.
LOWER
DISPLAY
UPPER
DISPLAY
PARA
METER
DEFAULT
DESCRIPTION
This function will be executed only if selected control action is PID & Auto tune is
Enable.
The Auto-tuning function can be initiated by setting this parameter to YES. The
decimal of LSB flashes till auto tuning function is in progress. During Auto-tuning,
The controller learns the process characteristics by itself & calculates required P, I
& D values.
User can cancel or abort this feature by setting this parameter to NO.
AUTO
TUNING
MODE
NO
USER GUIDE
: -
ON-OFF ACTION :
In this mode, Output (Relay/SSR) remains ON till actual temperature reaches to the set point value. On
reaching to SP, Output turns OFF & remains OFF till actual temperature drops down (in Heat Logic) or raises (in Cool Logic)
equal to hysterisis set by user. (As shown in Fig. 3.1 & 3.2)
AUTO TUNING MODE :
In this mode, Controller learns the process characteristics by itself and calculates the required P,I &
D values. It can be performed at any time after power ON but, it is best to start it when the process is at Ambient temperature
in order to minimize overshoot & undershoot. Auto tuning is applied in case of :
(1) Initial set up for a new process.
(2) Substantial change in SP from previous auto tuning value.
(3) Control accuracy is not satisfactory.
If the control performance by using auto-tuning is still unsatisfactory, User can apply further adjustments of P,I & D values as
shown in Table:3 below.
Fig: 3.1
HEAT LOGIC / ON-OFF
TIME
0
TEMP ( C)
HYSTERISIS
SP
ON
ON
ON
AMB
O/P
OFF
OFF
Fig: 3.2
TIME
COOL LOGIC / ON OFF
O/P
O/P
0
TEMP ( C)
AMB
HYSTERISIS
ON
ON
ON
SP
OFF
OFF
Proportional Band
Integral Time
Derivative Time
Slow Response
Over Shoot or Oscillations
Slow Response
Instability or Oscillation
Slow Response or Oscillation
High Over Shoot
Decrease PB
Increase PB
Decrease Int
Increase Int
Decrease Dt
Increase Dt
Adjust
Symptom
Solution
Table: 3
NC
: Normally Close terminal of relay
NO
: Normally Open terminal of relay
OP1
: Output 1
OP2
: Output 2
C.A.
: Control Action
CJC
: Cold junction compensation
CM
: Common terminal of relay
LWC
: Lead wire (Length)-
compensation
SP1
: Set Point Value (set temp.)
PV
: Process Value (actual Tmp.)
SSR
: Solid State Relay
T/C
: Thermocouple
ABBREVIATION :
9
OIM AI-7X82 V2.0 Page 9 of 9
413, New Sonal Link Service Industrial Premises Co-op Society Ltd,
Building No.2, Link Road, Malad (W), Mumbai - 400064.
Tel: 022-66939916/17/18;
E-mail : [email protected]
Website : www.itherm.co.in
Mfgd by: Innovative Instruments & Controls LLP
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