Elec Hotspot

Infrared Inspection on Electrical Installations at Hospitals Mohd Azmi Mohd Dani Faber Medi-Serve Sdn Bhd

 ABSTRACT Infrared (IR) thermography is one of the most valuable di agnostic tools for predictive maintenance. It is a cost effective solution available in varying capabilities, depending on how many technological options one can afford. IR systems can run the gamut from simple thermal sensors, to sophisticated thermal imagers with built-in color cameras complete with reporting software. With an infrared camera, it only takes minutes to look at systems and equipment to evaluate their current condition based on thermal patterns. Infrared thermography provides a non-contact, online or real-time evaluation of systems and equipment. For electrical systems, IR thermography can identify problems such as overheated components, poor connections, overloading, unbalanced loads and o verheating breakers, which if left unattended could lead to major breakdowns.

INTRODUCTION Based on historical infrared inspection data we have collected and archived on electrical systems in hospitals, we have found that poor or loose connections are the most frequently findings we detect.

CASE HISTORIES The infrared thermograms below show some sample IR images of ele ctrical installations at some of our hospitals. 121.8°C

87.4°C

120 80

100

80 60

60

40

40

20 18.5°C

Overhead lines: Insulation deteriorated

30.0°C

Main Switchboard: Unbalanced load

105.0°C

72.2°C 70

100

SP02  AR01

60 80

 AR01 LI01

50 SP01

60

40

40 38.8°C

Distribution Bo Board: Lo Loose ca cable co conn nne ection

32.1°C

Distribution Bo Board: Ov Overload at at Fu Fuse

Figure 1: Examples of electrical distribution images at our hospitals

InfraMation 2005 Proceedings

ITC 108 A 2005-06-01

Infrared Image

Thermal Profile °C

111.9°C

IR01

100

100  AR01

80

80

60

60

40 40

Line li01

27.7°C

Min 33.4°C

Max 108.8°C

Cursor   -

Figure 2: Pre-repairs: loose connection creates excessive excessive heat on cable end, thus producing a spike in the thermal pattern

The infrared image and thermal profile in Figure 2 shows a hot spot (at temperature 108.8 deg Celsius) on a cable connection at the distribution board. The overheating was caused by a loose or improper cable connection.  After corrective measures measures have been executed, the infrared infrared image (Figure 3) shows no hot spots and the thermal profile shows the normal operating temperature under working conditions. Infrared Image

Thermal Profile °C

62.0°C

IR01

60

60

 AR01

50 50

40 40

Line li01

30.9°C

Min 33.1°C

Max 42.8°C

Cursor   -

Figure 3: Post-repairs: The thermal pattern is uniform

The infrared image and thermal profile below (Figure 4) shows hot spot (at temperature 125.9 deg Celsius) on the cable connection at the main switchboard. The overheating was caused due to deteriorated cable insulation. Arrows show where the red and yellow phase cable insulation has deteriorated. Infrared Image  AR01

Thermal Profile 151.5°C

Photo

°C 150

IR01

LI01

140

 AR02 LI02

120

100

100 80

SP01

60 SP02

40 33.3°C

50 Line li01 li02 li03

Min 37.6°C 36.2°C -

Max 125.9°C 58.9°C -

Cursor   -

Figure 4: Pre-repairs: High temperatures on cable were detected.

InfraMation 2005 Proceedings

ITC 108 A 2005-06-01

Cable heated due to deteriorated insulation at the main switchboard

 After repairs to the cable, the infrared image reveals reveals no hot spots and the thermal thermal profile shows normal operating temperatures under working conditions. Infrared Image

Thermal Profile 71.8°C

Photo

°C

IR01

70

60 LI01

60

50

LI02

SP02

40

SP01

31.7°C

40

Line li01 li02 li03

Min 32.7°C 32.9°C -

Max 38.9°C 40.8°C -

Cursor   -

Figure 5: Post-repairs: The thermal pattern is uniform

Photo

Photo

Photo

Figure 6: Photos show the damaged cable after installation of a new one

SUMMARY The situation outlined in this paper, if not corrected, would have either led to fire, a short circuit or tripping of the circuit due to e xcessive heat on the cable, thus l eading to serious downtime in critical areas. By employing infrared thermal imaging techniques, we can actually predict the problem beforehand, thereby enabling us to rectify it, and the infrared images taken after corrective action shows them to be effective. It is very difficult to place a monetary value on the benefits realized from an infrared inspection program because the faults are found and repaired before failure occurs. The failure could be from a simple circuit tripping to a major fire due to excessive heat. By establishing a proper IR inspection program, the benefits are easily realized, as the reli ability and safety of electrical installations are ensured. At Faber Medi-Serve (FMS), we think of our infrared program as one of our key implementations.

 ACKNOWLEDGEMENTS The authors wish to thank the Infrared Training Center at FLIR Systems and Faber Medi-Serve Sdn Bhd for providing assistance and resources.

InfraMation 2005 Proceedings

ITC 108 A 2005-06-01