Alfa Laval EPC 50 Upgrades EPC 70 Separators

Marking cables: Use a labeling machine or colored zip ties to mark each cable entering the EPC 50 cabinet, indicating the terminal number and function (such as "DI-03 high water level switch").

Photo recording: Take photos of the wiring inside and outside the old cabinet, terminal layout, and PLC module model as reference for debugging.

Backup parameters: If the old system has readable parameters (such as using a handheld device or software), record the set values as much as possible (such as slag discharge interval time, temperature set value, pressure alarm threshold).

4.2 Demolition of old equipment

Disconnect all external cables (keep markings).

Remove the EPC 50 cabinet or panel and clean the installation area.

Check the insulation and shielding layer of the cable, and repair any damaged areas.

4.3 Installing New Hardware

Fix the EPC 70 control cabinet/panel to ensure reliable grounding.

Connect the cables one by one according to the terminal diagram. Pay special attention to the power line (AC 220V/24V DC), motor control line (contactor coil), and analog signal line (shielded single ended grounding).

Install steam valve actuator (if applicable), connect mechanical linkage and electrical cables.

Install the turbidity meter conversion board and connect the MT60 sensor signal line.

4.4 Power on initial inspection and software debugging

Insulation test: Use a 500V megohmmeter to measure the resistance of the power cable to ground, ensuring it is greater than 1M Ω.

Power supply inspection: Measure whether the 24V DC output in the control cabinet is stable and whether the touch screen starts normally.

I/O forced test:

Manually force output through touch screen, check motor start stop, slag discharge valve action, heater contactor engagement, etc.

Simulate input signals (such as short circuiting liquid level switches, using a signal generator to add 4-20mA), and confirm that the touch screen display value is consistent with the actual value.

Loading application software: Factory preset parameter files are downloaded to the controller via USB or Ethernet. If there is no preset file, manual input is required based on the original EPC 50 parameters.

PID loop tuning: If the steam valve actuator is replaced, the temperature control PID parameters should be re tuned. It is recommended to use the automatic tuning function (such as step response method) first, and then fine tune the proportional band and integration time.

4.5 No load and loaded trial operation

No load test: Start the motor without feeding the separator and observe whether the operating current, vibration, and temperature are normal. Perform manual slag discharge several times and confirm that the valve action timing is correct.

Establish water seal: Establish a water seal according to standard operating procedures and observe whether the water level control is stable.

Feed operation: gradually introduce the medium to be treated, monitor the turbidity, effluent pressure, and heater output after separation. Record a set of operational data (such as temperature, current, turbidity) and compare it with before the upgrade to verify the performance improvement.

Alarm simulation: Manually trigger high/low water level switch, high temperature switch, motor overload, etc., confirm that the alarm display and output are correct.

Common Problems and Solutions (Engineer Site Manual)

Problem 1: The touch screen displays "Communication Error" and there is no communication with the PLC

Reason: Loose Ethernet cable, mismatched IP address, or PLC not powered on.

Solution: Check the network cable plug; Confirm that the PLC and touch screen IP are in the same network segment; Measure the voltage of the PLC power supply.

Problem 2: The steam regulating valve does not operate or has abnormal opening

Reason: The polarity of the 4-20mA control signal is reversed, and the actuator has not undergone stroke calibration.

Solution: Check the wiring of AI/AO terminals; Follow the actuator manual to perform the 'Manual Automatic Calibration' procedure.

Question 3: The turbidity meter reading is always 0 or 100%

Reason: Sensor window contamination, loss of power supply to the conversion board, or short circuit in the signal line.

Solution: Clean the optical window of the turbidity meter; Check the LED indicator light on the conversion board; Measure the 4-20mA circuit with a multimeter.

Problem 4: The separator frequently discharges slag or does not discharge slag

Reason: Improper setting of slag discharge time parameters, overly sensitive turbidity meter threshold, and failure to establish water seal.

Solution: According to the original EPC 50 parameters, check the slag discharge interval, slag discharge time (usually 0.5-2 seconds), and turbidity setting value in EPC 70. Re establish the water seal procedure.

Question 5: Some input points have reversed states

Reason: The original EPC 50 used normally open contacts, the new system defaults to normally closed logic, or there was a wiring error.

Solution: Reverse the input or modify the wiring in EPC 70 software.

Upgraded operations and spare parts management

After completing the upgrade, the equipment enters the EPC 70 era. Suggest users to do the following: