What is the minimum acceptable temperature corrected insulation resistance value for a 480V emergency generator manufactured in 1965?

The minimum acceptable insulation resistance value for equipment such as a 480V emergency generator is crucial for ensuring safe and reliable operation. For generators manufactured around 1965, the industry standard for minimum insulation resistance is typically 1 Megohm. However, when specific conditions such as temperature and other environmental factors are taken into account, the acceptable value may be adjusted.

For equipment like generator sets, it is common practice to use a rule of thumb stating that the minimum acceptable insulation resistance should be significantly higher when considering older equipment or higher voltage levels. In many cases, a value of at least 1.5 Megohms is recommended to ensure that the insulation can withstand voltage stress and maintain safety over time. This higher threshold is particularly important for older machinery, which may have experienced insulation degradation over the years, making a higher standard necessary to ensure reliable operation.

Thus, the correct answer reflects this increased standard, acknowledging the potential for reduced insulation quality in older equipment and the need for a greater safety margin in insulation resistance values.