Watlow Series L Temperature Limiting Controller

2. The fuse is blown

3. The safety interlock switch is not closed (such as the oven door switch). 1. Use a multimeter to measure the voltage at terminal 1/2 and confirm that the power supply is normal

2. Check the fuse of the power circuit. If it is blown, check if there is a short circuit in the load

3. Check the status of the interlock switch to ensure it is closed. 1. Connect the power supply and reset the circuit breaker

2. Replace the 2A slow melting fuse and repair the load short circuit

3. Close the interlock switch (such as closing the oven door)

Abnormal temperature reading (high/low), ALARM light triggered incorrectly. 1. Sensor type configuration error (e.g. actual J type, K type selected when ordering)

2. Reverse the wiring of the sensor

3. Excessive wire resistance (RTD)

4. The ambient temperature exceeds 70 ° C. 1. Check the ordered model and actual sensor type to ensure consistency

2. Swap the positive and negative poles of the sensor and observe if the reading returns to normal

3. Measure the resistance of the RTD wire. If it is greater than 1 Ω, replace the thick wire or shorten the length

4. Measure the temperature inside the cabinet. If it exceeds the temperature limit, add a ventilation fan. 1. If the configuration is incorrect, it needs to be recalibrated at the factory

2. Correct the polarity of the sensor wiring

3. Replace RTD wires with 20 AWG or more

4. Improve cabinet ventilation and reduce ambient temperature

Unable to reset after triggering protection. 1. The temperature has not dropped below the "set point hysteresis"

2. LS series power on reset

3. External reset switch fault: 1. Measure the actual temperature and confirm if it meets the standard (if the set point is 100 ° C and the hysteresis is 3 ° C, it needs to be lowered to below 97 ° C)

2. LS series needs to be disconnected from the power supply for ≥ 3 seconds and then powered on again

3. Measure the reset switch with a multimeter to see if it conducts when pressed. 1. Wait for the temperature to drop to a safe range

2. Perform power-off reset (LS series)

3. Replace the faulty reset switch

Two LEDs flashing alternately (LS series) 1. Dual sensor temperature difference>20 ° C

2. Sensor polarity reversed

3. One of the sensors is faulty. 1. Measure the actual temperature of the two sensors and confirm if the temperature difference exceeds 20 ° C

2. Swap the positive and negative poles of one of the sensors and observe if the flashing stops

3. Short circuit the two sensor terminals separately and observe if they still flash. 1. Adjust the sensor installation position to reduce the temperature difference

2. Correct the polarity of the sensor

3. Replace the faulty sensor

2. Daily maintenance and calibration

(1) Regular maintenance (monthly)

Appearance inspection: The panel is not damaged, the LED indicator light is normal (power light on, ALARM light off), the wiring terminals are not loose or oxidized, and the sealing gasket is not aged.

Functional testing:

Simulate overheating: Heat the sensor with a standard temperature source and confirm that the ALARM light will turn on and output an action when the temperature reaches the set point.

Reset test: After the temperature drops to a safe range, press the RESET button (or power off) to confirm the output reset and ALARM light off.

Cleaning: Wipe the panel with a dry cloth to remove terminal dust. Do not use corrosive cleaning agents such as alcohol and acetone.

(2) Annual calibration

Calibration tools: standard temperature source (such as FLUKE 9170), high-precision multimeter (such as FLUKE 8846A), standard resistance box (for RTD calibration).

Thermocouple calibration steps:

Set the standard temperature source to the midpoint of the sensor range (such as J-type thermocouple 300 ° C), and record the controller display value after stabilization.

If the error is greater than ± 1%, the LV series can adjust the calibration offset through the panel (long press the UP+DOWN button for 5 seconds to enter calibration mode and adjust to the standard value); The LF/LS series needs to be returned to the factory for calibration.

RTD calibration steps:

Use a standard resistance box to output 119.4 Ω (corresponding to 100 ° C, DIN curve), and record the displayed value of the controller.

When the error exceeds the limit, adjust the RTD wire compensation (3-wire system) or return to the factory for calibration.

(3) Fault record

Suggest establishing maintenance logs to record the time, symptoms, troubleshooting process, and solutions of faults, with a focus on recording:

Determine the frequency of sensor failures (such as open circuits and short circuits) and determine whether to replace the sensor or improve the installation environment.

The triggering reasons for over temperature protection, such as frequent adhesion of heating tubes, require early replacement of aging components.

Typical application scenarios

1. Industrial oven temperature protection (LF series)

Requirement: The oven main controller (such as PLC+temperature module) controls heating and requires redundant protection to prevent the main controller output from sticking and causing overheating (such as setting a point of 180 ° C and triggering protection for overheating at 200 ° C).