The Shihlin Electric WT Series is a digital PID+Fuzzy temperature regulator designed for single-loop control in industrial automation applications. It combines a universal input stage—accepting 12 thermocouple types, 3 RTD types, and linear analog signals—with a dual-output architecture that supports relay, SSR voltage pulse, and 4‑20 mA current output modes. The PID+Fuzzy control algorithm provides faster convergence than conventional PID alone, particularly in systems with irregular thermal loads or frequent setpoint changes. An integrated heater break alarm (HBA) monitors the load current via a CT input and displays the heater current directly on the front panel, providing a diagnostic capability that eliminates the need for a separate current meter. Five standard DIN panel sizes (48×48 mm to 96×96 mm) allow a single product series to cover the full range of control cabinet cut-outs in a multi-zone machine.

Advanced Control & Overshoot Suppression

• PID+Fuzzy Dual Algorithm: In addition to standard PID control, the WT Series incorporates a fuzzy logic layer that dynamically adjusts the control output based on the rate and direction of temperature change—not just the magnitude of the deviation. This is particularly effective for low‑inertia heating systems such as packaging sealing bars or hot runner nozzles, where conventional PID controllers tend to overshoot during startup and oscillate under sudden load changes.
• Super SV Overshoot Suppression: The built‑in Super SV function actively limits temperature overshoot during initial heat‑up and after process disturbances. The function monitors the thermal response of the connected load and temporarily adjusts the effective setpoint to prevent the temperature from exceeding the target value during startup, then releases the suppression once the system approaches steady‑state. This protects heat‑sensitive materials and extends heating element life.
• Auto‑Tuning Function: The AT (Auto‑Tuning) function automatically determines the optimal PID parameters by executing a controlled heating cycle and analyzing the thermal response of the connected system. The calculated PID constants can be used immediately or manually fine‑tuned by the operator through the PID layer parameters.
• Heat/Cool Dual Output Control: The two outputs can be configured independently—one for heating, one for cooling—enabling a single WT controller to manage both sides of a thermal process. The cooling output can be configured for ON/OFF or PID+Fuzzy control, with a configurable deadband to prevent simultaneous heating and cooling.
• 8‑Segment Programmable Profiles: Each of the 2 groups supports up to 8 segments, enabling ramp and soak temperature profiles for batch thermal processes. Each segment can be independently configured with target temperature, ramp rate, and hold time.

Multi‑Level Alarm Architecture & Heater Break Detection

• 3 Independent Alarm Outputs, 17 Modes Each: Each alarm can be independently configured from a selection of 17 alarm types including high/low deviation, high/low absolute value, band alarm, heater break alarm, and timer-based alarms. The alarms can be assigned to either of the two control outputs or to a dedicated alarm output on the controller, providing flexible signaling for different process conditions.
• Heater Break Alarm (HBA) with CT Monitoring: An external current transformer (CT) connects to the WT Series and continuously monitors the load current drawn by the heating element. If the measured current drops below a user‑configurable threshold while the controller is calling for heat—indicating a broken heater or a failed SSR—the HBA relay output activates immediately. This prevents undetected heater failures from causing process temperature drops and product quality issues. The measured heater current is also displayed on the front panel, eliminating the need for a separate current meter to verify heater operation.

Flexible Communication & System Integration

• RS‑485 Modbus RTU/ASCII (up to 115200 bps): The WT Series supports both Modbus RTU and Modbus ASCII protocols over RS‑485 at baud rates up to 115 200 bps. This enables direct integration with Shihlin PLCs, HMIs, and third‑party SCADA systems via a single twisted‑pair network. All process values, setpoints, alarm states, and PID parameters are accessible through standard Modbus registers.
• RS‑232 Communication Option: For point‑to‑point communication with a single controller—typically used during commissioning or bench configuration—an RS‑232 interface is available as an alternative to RS‑485.
• Remote SV (Setpoint) Input: The target temperature setpoint can be supplied externally via an analog signal (4‑20 mA or 0‑10 V), enabling the WT Series to operate as a follower in cascade control loops or to receive its setpoint directly from a PLC without Modbus communication. This simplifies integration into existing PLC‑based control architectures.
• 3‑Level Data Lock: All parameters are organized into three access levels—User, PID, and Configuration. Each parameter can be individually hidden or locked via the data lock function, preventing unauthorized changes by untrained operators while allowing supervisors and engineers full access to PID tuning and hardware configuration parameters. This is critical in production environments where multiple shifts operate the same equipment.

Universal Input & Hardware Design

• 12 Thermocouple + 3 RTD + Linear Analog Inputs: The universal input stage accepts 12 thermocouple types (K, J, T, E, N, R, S, B, C, PL‑II, etc.), 3 RTD types (Pt100, JPt100, Cu50), and linear analog signals (4‑20 mA, 0‑20 mA, 0‑50 mV, 0‑5 V, 0‑10 V). Input type selection is made through configuration parameters—no hardware jumpers or module swaps are required. A single WT Series controller can replace multiple input‑specific controller variants in the spares inventory.
• 14‑bit A/D Resolution, 0.2% FS Accuracy: The 14‑bit analog‑to‑digital converter provides a resolution of 1 part in 16 384 of the full‑scale range. Combined with the 0.2% full‑scale accuracy and auto‑zero/auto‑span functions, the WT Series maintains long‑term measurement stability without requiring periodic recalibration.
• 10‑LED Output Percentage Display: A bar graph of 10 LEDs on the front panel directly displays the control output percentage (0‑100%), allowing operators to verify the controller's output status at a glance without navigating through parameter menus. This is particularly useful during commissioning and troubleshooting.
• 5 DIN Panel Sizes: Available in 48×48 mm, 48×96 mm, 96×48 mm, 72×72 mm, and 96×96 mm panel cut‑out dimensions—covering the complete range of standard DIN sizes for single‑loop temperature controllers. A single product series can be used across all control cabinets in a multi‑zone machine, simplifying procurement and maintenance.
• Wide‑Range Power Supply: All WT Series controllers operate from any supply voltage between 85 and 265 V AC at 50/60 Hz. A 24 V DC supply variant is optionally available, enabling direct integration into low‑voltage control panels.
• CE Certified (Highest EMC): All WT Series models carry CE certification and have passed the highest‑level EMC verification tests, ensuring reliable operation in electrically noisy industrial environments.

Applications

• Plastics extrusion and injection molding barrel and die zone temperature control
• Packaging machinery: heat sealing, blister forming, shrink‑wrap tunnels
• Industrial ovens, furnaces, and heat treatment equipment
• Hot runner injection molding systems requiring precise multi‑zone control
• Motorized valve positioning for heating and cooling circuits (with proportional motor valve control option)
• Single‑phase and three‑phase phase angle control using SCR or TRIAC modules