The electrical industry is transitioning towards SF₆-free switchgear. However, a large install base of SF₆-insulated equipment remains in operation which is not scheduled to be replaced. This equipment still requires leak monitoring to maintain insulation performance, identify gas loss and support emissions-management requirements.
The Chillcard NG provides continuous SF₆ measurement across selectable 0–1,000 ppm and 0–2,000 ppm ranges. Designed as an OEM (Original Equipment Manufacturer) sensing module, it can be integrated into sampling, monitoring and alarm systems.
Substantial releases of SF₆ will displace oxygen in poorly ventilated areas. The requirements of any personnel safety monitoring system regarding oxygen deficiency should therefore be considered separately from environmental leak monitoring.
The features of the Chillcard which apply specifically to SF₆ detection can be seen below in table 1.
Application Requirement Chillcard Feature Suitable measurement range Selectable 0-1,000 or 0-2,000 ppm ranges Continuous monitoring Designed for continuous power operation Measurement stability Dual channel NDIR measurement with environmental correction Fault awareness Reference channel monitoring and source-fault indication System integration Standard 4-20 mA output Industrial sampling Compatible with external pumps, tubing and filtration
Table 1. This shows how the design features of the Chillcard fit an array of requirements for SF₆ detection.
Non-dispersive infra-red (NDIR) instruments commonly use filament lamps. However, when continuously operated, the lamp can limit the lifetime of the light source. Ageing of the lamp can reduce optical output and increase maintenance requirements.
A filament light source can be affected by repeated thermal cycling, mechanical stress or changes in emissive output. When the light source becomes degraded, this can reduce signal strength which further increases maintenance requirements.
The low cost of ownership differentiates the Chillcard NG from its competitors. This is achieved by a robust device ready for many harsh industrial and agricultural environments which can have optional consumables added to protect the optics (filters for particulate matter and water droplets). These features reduce the need for servicing and lower maintenance costs, helping to create a sustainable and repairable product.
The Chillcard NG is designed for continuous monitoring with periodic maintenance requirements. It has a solid-state infrared source to reduce ownership cost, standard outputs for straightforward system integration and optional sample filtration to help reduce wear and protect the optics.
The Chillcard NG has two separate channels, one for measurements and one as a reference. The measurement channel responds to SF₆ absorption, while the reference channel provides a measure of how much the light source dims over time. This feature acts as a built-in fail-safe and reduces the likelihood of false zero readings.
Onboard pressure and temperature measurements are used to pressure and temperature-correct the reported gas concentration. This reduces the influence of changing environmental conditions on measurements and allows use of the Chillcard in a wide range of environments and atmospheric conditions but does not remove the need for periodic calibration.
The environmental conditions in which the Chillcard is rated for use in can be seen below in Table 2.
| Parameter | SF₆ configuration |
|---|---|
| Accuracy | Plus, minus 2% of full-scale division |
| Recommended sample flow | 0.2-1.2 L/min |
| Response time | T90 in 30 seconds |
| Warm-up | Full performance in 30 minutes |
| Cross-sensitivities | Ammonia and alcohol compounds |
| Operating conditions | 0-45 C, 800-1,150 mbar, 0-95% RH non-condensing |
Table 2. This shows the range of environmental conditions that the Chillcard can withstand. T90: time for OEM to reach 90% accuracy.
The Chillcard must be calibrated at yearly intervals to maintain accurate readings. This makes servicing easier to plan and ensures measurement performance is consistent throughout the product’s lifetime.
Figure 1. This is a picture of the Chillcard NG.
For ambient leak monitoring, sample points may be positioned where released SF₆ is likely to accumulate. As seen in fig. 1, a pump transports the sample through rubber tubing and filtration to the Chillcard NG. The host system reads the sensor’s output of 4-20 mA, and the SCADA (Supervisory Control and Data Acquisition) infrastructure provides the display, alarms and fault handling.
The Chillcard NG is manufactured under Edinburgh Instruments’ ISO 9001– certified quality management system and is designed to meet applicable CE and EMC requirements.
The Chillcard NG is an OEM module and is not independently approved for installation in potentially explosive atmospheres. If incorporated into hazardous area equipment, the complete design must be assessed and certified by the system manufacturer under the applicable requirements.
A large installed base of SF₆ switchgear will require leak monitoring for the remainder of its service life. The Chillcard NG provides continuous SF₆ measurement in an OEM format which can be integrated into existing sampling, alarm and SCADA systems.
Its solid-state light source and optional sample filtration support reliable operation with periodic maintenance requirements. Together, these features can help reduce servicing demands and total cost of ownership.
Industry standard 4–20 mA output allows integration into existing monitoring, alarm and SCADA infrastructure. An optional Ethernet connectivity provides additional flexibility for data logging.
