Every object has a distinct heat signature. An object’s infrared radiation is used in thermal imaging to improve the visibility of objects in the dark. Thermal imaging receptors detect an objects rendition and create an image based on that information. Thermal imaging can penetrate any obscurants such as smoke, haze, and fog. Thermal imaging works for Maintenance & Repair without ambient light since it detects the heat signature of an object.
It uses a thermal camera (Thermal imager) which is a heat sensor that is capable of detecting the slightest differences in temperature.
Since objects are rarely precisely the same temperature as other objects in their immediate environment, the thermal camera catches them, and they appear as a clear thermal image. Thermal imaging is, therefore, a powerful way of monitoring rotating equipment due to the heat they produce.
USING THERMAL IMAGING TO MONITOR GEARBOXES
Gearboxes are used in many industrial machines to vary the speeds of electric motors. Thermal imaging comes in to detect and protect overheating which is caused by lack of lubrication due to small amounts of lubricating oil.In the past, the maintenance method for gearboxes entailed a regular check on oil levels and replenishing when approaching critical levels. Checking oil levels in machines is a dangerous affair since the gearboxes are often in hazardous locations or inaccessible.
A thermal imager can be used to scan the surface temperature of the gear boxes on every critical equipment as determined by key operations, safety personnel, and maintenance. With this scan, it is possible to assess all assets whose malfunctions would threaten people, product or property. It is important to capture thermal images as well as digital images of the vital gearboxes. Even inaccessible gear boxes can be assessed by thermal imaging involves no contact.
The highest priority for repairs should be given to equipment that poses a safety risk. Monitoring provides an analysis of the cost of repair lost labor costs and lost production opportunity. When an overheating gearbox is discovered the thermal image provides hints as to why there is an abnormal operating temperature. Thermal imagers provide images using color to each pixel in an electronic image with a particular surface temperature. For these gear boxes and motors, overheating indicates a looming breakdown.
USING THERMAL IMAGING TO MONITOR MOTORS
A motor should be monitored while it is working under normal operating conditions. The exterior surface temperature captured by a thermal imager is indicative of temperatures inside the motor. The motor gets hotter on the outside with each rise of temperature inside. Most motors are designed to work in temperatures below 40 degrees Celsius.
Each motor monitored has a nameplate which indicates the maximum temperature allowed beyond the ambient temperature of that motor. For each motor, monitoring should be based on the cost of the motor, labor required to change the motor and the time lost on a particular line because of motor failure.
TROUBLESHOOTING GEARBOXES AND MOTORS
Troubleshooting is a way of fixing common problems especially applied in repair of failed processes after monitoring and identifying the possible causes of failure. There are different reasons why motors and gearboxes malfunction and the possible solution for each failure are different.
A motor might fail due to voltage overload. It typically happens due to a high-resistance connection in the switchgear or motor connection box. It can be pinpointed through infrared and confirmed using either a power quality analyzer or a multimeter. The other problem that would cause motor failure is bearing failure. When monitored, impending bearing failure is shown in images which indicate an overheating bearing.
Vibration analysis helps to determine the best course of action which would be to replace or lubricate the bearing. If the gearbox is found to be overheating, maintenance personnel can organize for follow-up measures by checking levels of oil, the metal content in the oil and oil quality. Alternatively, they can perform a vibration analysis.
It is of paramount importance to have a regular inspection routine and save the thermal images on a computer to track measurements over time. That way it is easy to pinpoint hot spots and give them special attention while in the case of repairs, it becomes easy to follow up and know whether they have been successful.