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Diagnosis of irregular movements of the hydraulic actuator: analysis of the proportional valve, analysis of contamination and signal check

Technical analysis: Troubleshooting erratic hydraulic actuator movement: proportional valve diagnostics, contamination a

Diagnosis of irregular movements of the hydraulic actuator: analysis of the proportional valve, analysis of contamination and signal check

1. Problem Description and Scope of Influence

This manual is dedicated to the diagnosis of irregular movements of the hydraulic actuator, which occur due to problems with the proportional valve, system contamination, or signal integrity failure. This applies to equipment that uses hydraulic systems with proportional control, such as hydraulic presses, clamping units, hydraulic rotating mechanisms, and other industrial devices. The behavior is considered critical, as irregular movements may lead to failure or damage to the equipment.

2. Preventive Measures

Use personal protective equipment (PPE): gloves, safety goggles, helmets, special footwear.
Perform energy isolation (LOTO): before diagnostics, disconnect the energy and install all locking devices.
Carefully detect trapped energy: open the valves, check for pressure presence, use appropriate tools.

3. Required diagnostic tools

Tool Name Model/Specification Measurement range Purpose
Multimeter Fluke 87V 0–2000 Ω, 0–600 V, 0–20 A Electrical connections and signals check
Vibration Analyzer Brüel & Kjær 3580 0–10000 Hz, 0–2000 m/s² Vibration Characteristics Analysis of the Valve
Thermal camera FLIR T1030sc -20°C to 550°C, 0.05–1.0 µm Detection of uneven heating of the valve
Signal amplifier Keysight N2800 0–10 V, 0–100 mA Valve proportional signal check
Comprehensive Tester Keysight 34461A 0–2000000000 Ω, 0–10000000000 V Detailed electrical parameter check

4. Initial assessment: checklist

Item Action
1 Check current operating conditions of the system
2 Take note of the latest changes in the system
3 Check alarm history and errors
4 Check the system pressure
5 Check vibration characteristics
6 Check the valve temperature
7 Check proportional valve signal

5. Systematic Diagnostic Scheme

  1. Check the actuator movement for irregularity.
    1. If the movement is irregular:
      1. Check the pressure in the system using a manometer.
        1. If pressure is higher than 250 bar: ensure the valve is correctly set.
        2. If pressure is below 100 bar: check for leaks and filter.
      2. Check the valve vibration.
        1. If vibration is higher than 10 mm/s: perform the valve disassembly for inspection.
      3. Check the valve temperature.
        1. If temperature is above 80°C: check the filter and presence of contamination.
      4. Check the proportional valve signal.
        1. If signal is above 10 mA: check electrical connections.
        2. If signal is below 1 mA: check the power supply.
    2. If the movement is regular: check other components of the system.

6. Cause Matrix for Water Ingress

Symptom Possible cause Diagnostic Check Expected result
Irregular movements of the actuator Incorrect valve setting Pressure and signal check Pressure within the range 100–250 bar, signal within the range 1–10 mA
Irregular movements of the actuator Contamination of the system Contamination Analysis Contamination level ≥ 15 μm
Irregular movements of the actuator Damaged valve Visual inspection and vibration measurement Vibration ≥ 10 mm/s
Irregular movements of the actuator Incorrect signal Signal Check Signal not in the range of 1–10 mA
Irregular movements of the actuator Cable damage Resistance measurement Resistance > 1000 Ω

7. Analysis of Causes of Water Ingress

7.1. Incorrect Valve Adjustment

Incorrect valve adjustment may lead to irregular movements. This may occur due to damaged regulating discs, deviation from the design structure, or incorrect parameter setting. If the valve is not properly adjusted, it cannot accurately respond to the signal, resulting in unstable movements. Check the valve pressure and signal, and if they are not within 100–250 bar and 1–10 mA respectively, perform the adjustment.

7.2. Contamination of the system

Contamination of the system may lead to hydraulic fluid rejection and uneven valve opening. This may result in irregular movement of the actuator. Perform contamination analysis at ≥ 15 μm. If contamination is detected, perform system cleaning and replace the filter.

7.3. Valve Damage

Damaged valve may cause irregular movements due to lack of opening accuracy. Perform a visual inspection and measurement of valve vibration. If vibration ≥ 10 mm/s, the valve needs to be replaced.

7.4. Incorrect Signal

Incorrect signal may cause irregular movement of the actuator due to incorrect command transmission. Measure the valve signal. If the signal is not within 1–10 mA, check the electrical connections and power supply.

7.5. Cable Damage

Damaged cable may cause irregular movements due to a reduction in the electrical signal. Measure the cable resistance. If the resistance > 1000 Ω, the cable needs to be replaced.

8. Step-by-step procedure for correction

8.1. Correction of Incorrect Valve Settings

  1. Measure the pressure in the system.
  2. If the pressure is higher than 250 bar, check the valve settings.
  3. If the pressure is below 100 bar, check the filter.
  4. Check the valve signal.
  5. If the signal is above 10 mA, check the electrical connections.
  6. If the signal is below 1 mA, check the power supply.
  7. Set the valve to 100–250 bar and 1–10 mA.
  8. Check the actuator movement.

8.2. Cleaning of the system

  1. Perform contamination analysis.
  2. If contamination ≥ 15 μm, clean the system.
  3. Replace filter.
  4. Check the actuator movement.

8.3. Valve Damage Repair

  1. Perform a visual inspection of the valve.
  2. If damage is detected, replace the valve.
  3. Check the actuator movement.

8.4. Correction of Incorrect Signal

  1. Measure the valve signal.
  2. If the signal is not within 1–10 mA, check the electrical connections.
  3. If the signal is not within 1–10 mA, check the power supply.
  4. Check the actuator movement.

8.5. Cable Damage Repair

  1. Measure the cable resistance.
  2. If resistance > 1000 Ω, replace the cable.
  3. Check the actuator movement.

9. Prevention Methods

Cause Preventive strategy Monitoring method Recommended interval
Incorrect valve setting Regular Valve Adjustment Pressure and signal measurement Every 6 months
Contamination of the system Regular filter replacement Contamination Analysis Every 3 months
Damaged valve Regular valve inspection Visual inspection Every 6 months
Incorrect signal Regular inspection of electrical connections Signal measurement Every 6 months
Cable damage Regular cable inspection Resistance measurement Every 6 months

10. Parts and Components

Part Description Specification When to replace Category UNITEC-D
Proportional valve 10–250 bar, 1–10 mA After 6 months or detection of damage Category 200
Hydraulic Fluid Filter 10–250 bar, 1–10 mA After 3 months or detection of contamination Category 210
Signal cable 1–10 mA After 6 months or detection of damage Category 220
Power cable 1–10 mA After 6 months or detection of damage Category 230

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11. References

  • DSTU 2836-94 - Technical specifications for hydraulic systems
  • EN 12900-1:2012 - Hydraulic systems: general requirements
  • ISO 10426-1:2012 - Hydraulic Valves: Test Methods
  • UNITEC-D Maintenance Guide: Proportional Valves

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