Watlow Series F4P Temperature/Process Controller

Requirement: Control the temperature of the refrigerated compartment (external circuit, 0 ℃) by adjusting the compressor (internal circuit, -10 ℃) to avoid temperature fluctuations in the compartment.

Configuration:

External circuit (cabin temperature): Input 1 connected to Pt100 RTD (-30-50 ℃), set point 0 ℃, PID parameters (proportional band 5 ℃, integration time 10 minutes).

Internal circuit (compressor): Input 3 Pt100 RTD (-50-0 ℃), set point determined by external circuit output (range -15-0 ℃), PID parameters (proportional band 2 ℃, integration time 3 minutes).

Output 1A: Control compressor (cooling), output 1B: Control heater (insulation).

Advantages: The internal circuit quickly responds to the external circuit requirements, reduces cabin temperature overshoot (such as rapid cooling after opening the door), and improves control accuracy.

3. Valve positioning control (fluid flow)

Requirement: Control pipeline flow, adjust valve opening, potentiometer feedback valve position (0-100% corresponds to 100-1200 Ω), flow target 50%.

Configuration:

Input 1: Flow sensor (4-20mA, 0-100% flow).

Input 3: Potentiometer (100-1200 Ω, feedback valve position), set to "Posici ó n de v á lvula", dead zone 1%.

Output 1A: Control valve to close (relay), output 1B: Control valve to open (relay), PID parameters (proportional with 5%, integration time of 2 minutes).

Advantages: Closed loop control based on position feedback avoids flow deviation caused by valve jamming, and dead zone setting reduces frequent actions.