Qatar Low-Voltage Busbar Temperature Measurement Procedure

Low-voltage busbar temperature in Qatar should be measured using non-contact infrared sensors, following IEC 61439 thermal limits and KAHRAMAA guidelines for high-ambient conditions.

Regulatory and Design Context

In Qatar, low-voltage switchgear and busbars are governed by IEC 61439-1, which sets the maximum permissible temperature rise for bare copper busbars at 105 K above a 35°C reference ambient, resulting in an absolute busbar temperature limit of 140°C. However, Qatar's summer ambient temperatures can reach 40–50°C, reducing the thermal margin and requiring derating of busbars to prevent overheating and insulation failure.

KAHRAMA

A evaluates the LV panel up to the vertical busbar, ensuring compliance with local safety and thermal standards. Measurement MethodologyNon-contact infrared (IR) sensors are recommended for busbar temperature monitoring because they provide accurate, instantaneous readings while remaining electrically isolated from live conductors. Key steps include: Sensor Selection and PlacementUse IR sensors suitable for the expected temperature range (-20°C to 1000°C).

Mount sensors at a safe distance from the busbar to avoid electric arcs. For wide busbars, use wide-angle optics (2: 1); for narrow or high-voltage busbars, use narrow optics (20: 1) to maintain measurement accuracy. Paint the busbar surface with a high-emissivity coating to improve IR measurement reliability.

Monitoring Points

Focus on busbar joints and bolted connections, as these are the most susceptible to overheating. Typically, six sensors per switchgear cabinet are used: three on input busbars and three on output busbars.

Data Logging and Alarm Integration

Connect sensors to a central hub (e.g., PM180 touch screen) for real-time display, configuration, and data logging to MicroSD. Integrate with SCADA systems via Modbus TCP for centralized monitoring and alarm management.

Measurement Considerations

Ensure the sensor angle relative to the busbar is appropriate; measurements at 90° yield circular spots, while lower angles produce elliptical spots. Continuous monitoring allows early detection of joint deterioration and prevents thermal overload.

Safety and Operational Notes

Ensure busbars are derated according to ambient temperature and load diversity factors. Verify that connected devices (circuit breakers, terminals) do not have lower temperature limits than the busbar itself. Maintain ambient temperature awareness, as Qatar's hot and humid climate can significantly reduce thermal headroom.

Periodically inspect and recalibrate IR sensors to maintain measurement accuracy. By following this procedure, engineers can ensure safe operation of low-voltage busbars in Qatar, comply with IEC 61439 thermal requirements, and meet KAHRAMAA approval standards while enabling proactive maintenance through continuous temperature monitoring.