Diagnostic Help: Debugging continuous safety line outages

1. Problem description and scope

This reference is devoted to diagnostic methods for solving continuous cases of exiting the safety line (Safety System Trips). These cases occur in industrial installations with automated safety, such as access control systems, safety sensors, switchboards and safety modules. Continual incidents of safety line departures can be critical as they lead to production stoppages, product loss and impact on personnel safety. They can be caused by a variety of reasons, including incorrect placement of sensors, broken electrical connections, or environmental influences.

2. Preventive measures

Use personal protective equipment (PPE): buckets, gloves, glasses, breathing filters. Perform Lockout and Tag Out (LOTO): Before performing any diagnostic work, turn off power, install interlocks, and tag the device to prevent unintended activation. Protection against stored energy: remove residual energy from the circuit before working with the circuit. Turn off the power supply: turn off the power of the device, install blocking devices, perform marking.

3. Necessary diagnostic tools

4. First assessment: list of observations

5. Systematic diagnostic scheme

1. Symptom Confirmation: Determine if the security system is continuously disabled.
2. Measuring electrical parameters: Use a multimeter to measure voltage, current, and resistance.
1. Measure the voltage at the input and output connections.
2. Check whether there is a deviation from the nominal values: 230 V ± 10%.
3. Check the current: 0.05-0.1 A (allowed range).
4. Check the resistance: 0.1-10 Ω (allowed range).
3. Check security sensors: Use the sensor data analyzer to measure signals.
1. Measure the input signal: 0-10 V, 0-20 mA.
2. Check whether there are deviations from the nominal values: 0.02-0.1 V, 0.05-0.2 mA.
3. Check vibration: 0-100 mm/s (allowed range).
4. Environment detection: Use a thermal camera to detect overheated areas.
1. Test temperature: -20°C to 550°C.
2. Check if there is a deviation from the permissible range.
5. Diagnosing output connections: Use a vibration analyzer to detect unevenness.
1. Measure vibration: 0-100 mm/s.
2. Check if there is a deviation from the permissible range.

6. Matrix of causes of defects

7. Analysis of root causes

7.1 Sensor signal mismatch

Reason: Deviation from nominal values of safety sensor signals can be caused by sensor malfunction, incorrect location, or environmental exposure. Diagnosis: Use the sensor data analysis tool to measure signals. Impact: Incorrect signals cause a continuous shutdown of the security system.

7.2 Incorrect setting of the safety relay

Reason: Incorrectly setting the safety relay can cause the system to shut down continuously. Diagnosis: Check the safety relay settings. Impact: An incorrect setting causes the security system to be disabled continuously.

7.3 Violation of electrical connections

Reason: Broken electrical connections can lead to signal loss or incorrect measurement. Diagnosis: Use a multimeter to measure resistance and voltage. Impact: Incorrect connections cause the system to shut down continuously.

7.4 Impact of external factors

Reason: Environmental effects such as temperature or vibration may cause the security system to be permanently disabled. Diagnosis: Use a thermal camera to measure temperature and a vibration analyzer to measure vibration. Impact: Environmental exposure results in continuous shutdown of the system.

8. Step-by-step repair procedure

8.1 Sensor signal mismatch

1. Use the sensor data analysis tool to measure the signals.
2. Check whether there are deviations from the nominal values: 0.02-0.1 V, 0.05-0.2 mA.
3. If a deviation is detected, check the safety sensor for serviceability.
4. Replace the new safety sensor or repair the old one.
5. Check the sensor settings and set them to nominal.
6. Measure the signals again to confirm.

8.2 Incorrect setting of the safety relay

1. Check the safety relay settings.
2. Set the settings to nominal.
3. Check that the measurements correspond to the nominal values.
4. Remeasure the safety system to confirm.

8.3 Violation of electrical connections

1. Use a multimeter to measure resistance and voltage.
2. Check whether there is a deviation from the nominal values: 0.1-10 Ω, 230 V ± 10%.
3. If a deviation is detected, check the connection for serviceability.
4. Make new connections or repair old ones.
5. Check the connection settings and set them to nominal.
6. Remeasure the safety system to confirm.

8.4 Impact of external factors

1. Use a thermal camera to measure the temperature.
2. Check for deviations from nominal values: –20°C to 550°C.
3. Use a vibration analyzer to measure vibration.
4. Check whether there is a deviation from the nominal values: 0-100 mm/s.
5. If a deviation is found, correct the influence of the environment.
6. Set nominal conditions and test the safety system.

9. Prevention

10. Spare parts and components

View our e-catalog: https://www.unitecd.com/e-catalog/

11. Main standards and documents

• DSTU 4769:2013 — Safety in industrial installations
• EN 60204-1:2016 - Safety of electrical equipment
• ISO 13849-1:2015 - Automation security
• CE, UkrSEPRO
• Manufacturer's OEM documents
• UNITEC-D recommended documents