TE Technology TC-36-25-RS485 - Manual (Page 33)

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3.2 Enter the following parameters:
PROPORTIONAL BANDWIDTH: 20
INTEGRAL GAIN: 0
DERIVATIVE GAIN: 0
3.2.1 Allow the TE device to reach steady state. Incrementally reduce the bandwidth setting, allowing the controller to
reach steady‐state at each increment, until the temperature just begins to oscillate. At this point, the bandwidth is
too small. Note the bandwidth setting that just caused the system to oscillate and note the time period of
oscillation in minutes. The time period will be used later for determining the integral gain and derivative gain
settings.
NOTE: The system temperature will likely begin to oscillate before reaching the set point temperature. This is
normal.
3.2.2 Multiply the current proportional bandwidth setting by 2.2, and enter it as your new PROPOROTIONAL
BANDWIDTH setting. The temperature should stabilize and maintain a steady temperature near the set point.
3.2.3 The integral gain is calculated as follows: I = 0.54/T where I is the integral gain, and T is the time period, in minutes,
determined in section 3.2.1. Enter this value into the INTEGRAL GAIN.
For example, suppose the system’s period of oscillation with the appropriately set proportional bandwidth was 75
seconds (1.25 minutes). The suggested integral gain is therefore:
I = 0.54/1.25 minutes = 0.43 repeats/minute
3.2.4 The derivate gain is often times difficult to apply and might cause more trouble than it is worth. If you are not
experienced in process control, you may be better off leaving the DERIVATIVE GAIN set to zero.
If you decide to use derivative gain, the other values should be adjusted first.
a) Instead of multiplying the initial bandwidth setting by 2.2, multiply it by 1.7, and enter this as the new
PROPORTIONAL BANDWIDTH setting.
b) Calculate the integral gain as follows: I = 1.2/T, and enter this into the INTEGRAL GAIN setting.
c) Calculate the derivative gain as follows: D = 0.075 x T, and enter this into the DERIVATIVE GAIN setting.
Setup of the TC‐36‐25 RS485 is now complete. However, the proportional, integral, and derivative settings are
approximate settings and might need further minor adjustments.
You might also want to save your settings to EEPROM for future recall (see section 2.4.1)