Understanding Utilisation Factor in Power Stations

The question asks to identify the term used for the ratio of the maximum demand on a power station to its rated capacity. Let's break down the definition and the options provided.

Definition of Utilisation Factor

The utilisation factor is a measure used in power system analysis to describe how effectively the capacity of a power station is being used.

Specifically, it is defined as the ratio of the actual maximum power demanded from the power station over a certain period to the total rated capacity of the power station.

The formula can be expressed using LaTeX:

$$ \text{Utilisation Factor} = \frac{\text{Maximum Demand on Power Station}}{\text{Rated Capacity of Power Station}} $$

A utilisation factor close to 1 indicates that the power station is operating at or near its full capacity during peak times, while a lower value suggests underutilization.

Analysis of Options

Let's examine each option to understand why utilisation factor is the correct answer:

1. Demand Factor

Demand Factor is defined as the ratio of the maximum demand of a system (or part of a system) to the total connected load on that system.

Formula:

$$ \text{Demand Factor} = \frac{\text{Maximum Demand}}{\text{Total Connected Load}} $$

This factor compares the peak load to the total potential load if all connected devices were used simultaneously. It's different from the question's definition.

2. Utilisation Factor

Utilisation Factor is defined as the ratio of the maximum demand on the power station to the rated capacity of the power station.

Formula:

$$ \text{Utilisation Factor} = \frac{\text{Maximum Demand on Power Station}}{\text{Rated Capacity of Power Station}} $$

This definition perfectly matches the description given in the question.

3. Plant Use Factor

Plant Use Factor (also known as Capacity Factor) is defined as the ratio of the actual units generated (in kWh) in a given period to the possible maximum units that could have been generated if the plant ran at its full rated capacity throughout the period.

Formula:

$$ \text{Plant Use Factor} = \frac{\text{Actual Energy Generated (kWh)}}{\text{Rated Capacity (kW)} \times \text{Time Period (hours)}}} $$

This factor considers the energy generated over time, not just the peak demand relative to capacity.

4. Diversity Factor

Diversity Factor is defined as the ratio of the sum of the individual maximum demands of the various subdivisions of a system (or part of a system) to the maximum demand of the whole system.

Formula:

$$ \text{Diversity Factor} = \frac{\text{Sum of maximum demands of all consumers}}{\text{Maximum demand of the whole system}} $$

This factor accounts for the fact that not all consumers reach their maximum demand simultaneously. It relates to the summation of demands across different users, not the station's overall utilization.

Comparison Summary

Here's a quick comparison:

Based on the definitions, the term that specifically describes the ratio of the maximum demand on the power station to its rated capacity is the utilisation factor.