Overall Equipment Effectiveness (OEE) is a metric used to measure the performance of a manufacturing process or equipment. It takes into account three factors: Availability, Performance, and Quality. While it is true that when planned downtime is 100 percent, certain calculations in the OEE formula may result in division by zero, leading to undefined values for individual components like Availability (A), Performance (P), and Quality (Q). Let's break it down:

Availability (A): This factor represents the ratio of the actual operating time to the planned production time. When planned downtime is 100 percent, it means that the equipment is not available for production at all. In this case, the availability calculation becomes undefined since it involves dividing the actual operating time by zero.

Performance (P): Performance is the ratio of the actual production rate to the maximum achievable production rate. When the equipment is not available for production due to 100 percent planned downtime, the performance calculation is also undefined. This is because the actual production rate would be zero, and dividing zero by zero is an undefined operation.

Quality (Q): Quality refers to the ratio of the number of good units produced to the total number of units produced. While quality can still be measured even during planned downtime, it becomes less meaningful when there is no actual production taking place.

Given that Availability (A), Performance (P), and Quality (Q) cannot be determined when planned downtime is 100 percent, the overall OEE value, which is the product of these three factors, would also be undefined. Consequently, the Utilization and TEEP (Total Effective Equipment Performance) calculations would also be undefined, as they depend on the availability and overall OEE values.

In practical terms, when planned downtime is 100 percent, it indicates that the equipment is intentionally scheduled to be non-operational for the entire planned duration. In such cases, OEE may not be a suitable metric for evaluating equipment performance since its calculations rely on actual operating time and production rates.

Thanks ChatGPT

OEE calculations are only applied to *scheduled* production time.

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