SDX – Smart Device Expert Circuit-breaker Monitor

Circuit breakers are widely employed to protect and switch electric power systems. Therefore, they must be in perfect operating condition in order to maintain system reliability and safe installations.

Online monitoring and condition assessment using the expert Circuit-breaker Monitor – SDX ensures failure reductions through early detection and diagnosis of equipment defects hence maintaining continuity of the power supply.

The safe operation of circuit breakers employed in electric power systems depends on reliable operation of the different sub-systems that make up the breaker – the mechanism that activates and stores energy, the mechanisms that trigger and move the main contacts and the insulation system. Based on measurements and algorithms, the SDX issues alarms in the event of abnormalities as well as maintenance reminders. These alarms and warnings are configured by the user and are communicated via a colour coded system, permitting the user to rapidly check the status of the disconnect switch.

• Green – Breaker working correctly. No maintenance is needed;
• Blue – Breaker working correctly. Maintenance reminder;
• Yellow – Minor abnormality;
• Red – Major abnormality.

The SDX has advanced connectivity including redundant Ethernet ports -fibre optics or RJ45, wireless Wi-fi network, as well as IEC61850, HTTP protocols for embedded web pages, FTP for remote access to files and databases and SMTP to send alarm emails.

In this setup, the SDX operates with embedded SQL databases, facilitating safe and efficient storage, access to historical data and the complete integration with remote online monitoring systems.

The SDX analyses measured values with engineering algorithms to obtain divers information to be used for diagnosis and prognosis, such as:

• Instantaneous speed, acceleration and average speed of the main contact;
• Main contact stroke, overtravel and bounce during operation;
• Main contact opening, closing, pre-insertion and movement times;
• Auxiliary contact opening and closing times during operation;
• Arc, pre-arc, establishment, interruption and re-ignition times;
• Integration of arc currents, separated into arc regions and nozzles;
• Percentage of wear in main contacts and circuit-breaker nozzle contacts;
• Synchronisation times between poles with independent activation;
• Opening and closing coil reaction and pulse times;
• Coil resistance and coil continuity during operation;
• Minimum and maximum coil voltages during operation;
• No. of operations and time the switch has been in service (total and since last maintenance service);
• Average operations and extrapolated time for circuit-breaker maintenance;
• Motor power signature, power spent and times during charging;
• No. of operations and time the motor has been in service (total and since last maintenance service);
• Average daily operations and time remaining until next pump maintenance;
• Excessive hydraulic pump use or long period for spring loading;
• Faults in mechanism after operation of the circuit-breaker;
• Mechanism heater operation due to low temperature;
• Control and motor supply under and overvoltage;
• StatusCoherence of circuit-breaker signalling contacts;
• Leakage rate and time for SF6 gas recharge;
• SF6 pressure, real and standardized at 20 ºC;
• Operation of pole heaters in accordance with temperature.

The SDX supervises many variables to perform the above diagnostics, such as:

• Displacement of the main contact during operation;
• Line currents;
• Opening and closing coil voltages and currents;
• Drive motor voltage, current and power;
• Power accumulator displacement;
• Hydraulic pressure;
• Mechanism and environmental temperatures and heater current;
• Control voltages;
• Status of circuit-breaker signalling contacts;
• SF6 density and temperature;
• Alarms and circuit breaker blocking due to SF6 pressure;
• SF6 heaters currents.

Accessories

• External Split Core Clip-On CTs
• Auxiliary Voltage Transformers
• PT100Ω temperature sensors at 0ºC
• Ambient temperature RTD Weather Shield
• Incremental Encoderto measure the main contact position
• Surge Protection device for Encoder and Digital Density and Temperature Sensor – DEP