Auber Instruments SWA-2441B Manual de instruções - Página 4

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AUBER INSTRUMENTS

and used for the system. Please note that auto-tuning is only for PID control

mode. There is no need for auto-tune when using ON/OFF mode (when P = 0).

To stop the auto-tuning, enter the parameter setting mode, set At = OFF. Then,

the previous PID parameters values are resumed.

AT start

Figure 5. Auto tuning

85.5

Time

SET 3S

AL1

999.9

Alarm1 Setting

SET

AL2

Alarm2 Setting

SET

0.0

Input Offset

SET

15.0

Proportional Constant

SET

240

Integral Time

SET

Derivative Time

SET

OFF

Auto Tune

SET

Cycle Time

SET

1.0

Hysteresi s Band

SET

Hy1

Hy 1

1.0

Alarm 1 Hysteresi s Band

SET

Hy2

Hy 2

1.0

Alarm 2 Hysteresi s Band

SET

Deci m al Point Position

SET

Figure 4. System setup flow chart.

4.3 Control action explanations

4.3.1 PID

The values of the P, I, and D parameters are critical for good response time,

accuracy and stability of the system. Using the Auto-Tune function to

automatically determine these parameters is recommended for the first time

user. If the auto tuning result is not satisfactory, you can manually fine-tune the

PID constants for improved performance.

2021.01

AT end

AT calculation

OFF

ON/OFF

PID

Display Unit

SET

dih

DIH

999.9

Input High Limit

SET

Dil

DIL

Input Low Limit

SET

OPA

Output Mode

SET

Input Type

SET

LOCK

Lock

Configuration Privi l ege

SET

outh

OUTH

100

Output High Limit

SET

COOL

Cool

OFF

Cooling Control

SET

ALP2

ALP 2

Alarm 2 Definition

SET

ALP1

ALP 1

Alarm 1 Definition

Proportional Constant (P): P is also called the proportional band. Its unit is

the degree of temperature. For example, P = 50 means the proportional band

is 50 degrees. Assuming the set temperature SV = 200. When integral, I, and

derivative, d, actions are removed - the controller output power will change

from 100% to 0% when temperature increases from 150 to 200 ° C. The

smaller the P value is, the stronger action will be for the same temperature

difference between SV and PV. Please note: for on/off control mode, P is

set to 0.

Integral time (I): Brings the system up to the set value by adding to the output

that is proportional to how far the process value (PV) is from the set value (SV)

and how long it has been there. When I decreases, the response speed is

faster but the system is less stable. When I increases, the response speed is

slower, but the system is more stable. When I = 0, the integration is turned off.

It becomes to a PD controller that is useful for very slow system.

Derivative time (d): Responds to the rate of PV change, so that the controller

can compensate in advance before |SV-PV| gets too big. A larger number

increases its action. Setting d-value too small or too large would decrease

system stability, causing oscillation or even non-convergence. Normally, d is

set to ¼ of the I value. However, when the controller is in on/off mode (P = 0)

and cooling control is turned on, d means Delay Timer of the Anti-Short Cycle

Delay (Asd) function. The delay time ranges from 1-200 minutes. (See 4.3.3

for details).

4.3.2 On/off control mode

It is necessary for inductive loads such as motors, compressors, or solenoid

valves that do not like to take pulsed power. It works like a mechanical

thermostat. When the temperature passes the SV+Hy, the heater will turn off.

When the temperature drops back to SV-Hy, the heater will turn on again. (In

cooling mode, the cooler turns on when temperature passes SV+Hy, and turns

off when temperature drops back to SV-Hy). To use the on/off mode, set P =

0 and Hy to the desired band. Then I and D parameters are not used when

controller is in heating mode. It can be left at any value. In the cooling mode,

the D value is used for Anti-Short Delay time. Its value is in minutes (See 4.3.3

for details).

4.3.3 Cooling control

When controller is used for cooling control and load is a compressor, it should

not turn on the compressor when its refrigerant is at high pressure (just after

turned off). Otherwise, the compressor can be damaged in short time. Two

methods are commonly used to prevent the rapid cycling of the compressor.

One is to use on/off control mode (instead of the PID control mode) with wide

enough hysteresis band, and long cycle rate. The other is to use the Anti-Short

Cycle Delay (ASd) function. ASd establishes the minimum time that the N.O.

contacts remain open (after reaching cutout) before closing again. The delay

overrides any Load Demand and does not allow the N.O. contacts to close until

the set time-delay value has elapsed. ASd gives time to release the refrigerant

pressure through evaporator. This controller allows the user to use both

methods to protect the compressor. You should set the P = 0 for on/off mode.

Hy should not be less than 2 degrees unless you really need a tight control. The

cycle rate should be set for 20 second or longer. The D is typically set to 4- 6

(minutes).

4.3.4 Manual mode

Manual mode allows the user to control the output as a percentage of the total

heater power. It is like a dial on a stove. The output is independent of the

temperature sensor reading. One application example is controlling the strength

of boiling during beer brewing. You can use the manual mode to control the

boiling so that it will not boil over to make a mess. The manual mode can be

switched from PID mode but not from on/off mode. This controller offers a

"bumpless" switch from the PID to manual mode. If the controller outputs 75%

of power at PID mode, the controller will stay at 75% when it is switched to the

manual mode, until it is adjusted manually. See Figure 3 for how to switch the

display mode. To activate the manual control, pressing the ◄ key for 3

seconds or until the bottom display shows H at the most left digit. The H

indicating the controller is in manual mode. The number at the right is the

percentage of output. Press the ▼or ▲key to adjust the power. To switch back

to PID mode, pressing the ◄ key for 3 seconds or until the H disappeared.

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