Demand Factor MCQ Quiz - Objective Question with Answer for Demand Factor - Download Free PDF

Explanation:

Demand Factor

Definition: The demand factor is a measure used in electrical engineering to describe the ratio of the maximum demand of a system (or equipment) to its total connected load. It provides insight into how efficiently the connected load is being utilized during peak demand periods. Mathematically, the demand factor is expressed as:

Demand Factor (DF) = Maximum Demand ÷ Total Connected Load

The demand factor is primarily used in power system analysis and design to ensure that electrical installations are appropriately sized and optimized for their intended use.

Working Principle:

The demand factor is always less than or equal to 1 because the maximum demand of a system cannot exceed the total connected load. In most real-world scenarios, the demand factor is less than 1, as not all connected devices and equipment are simultaneously operating at their maximum rated capacity.

Applications:

• Electrical load calculation for designing power systems.
• Optimizing the size of transformers, generators, and distribution systems.
• Energy efficiency analysis to identify potential areas for reducing power consumption.

Correct Option Analysis:

The correct option is:

Option 3: It is always less than or equal to 1.

This statement is correct because the demand factor is a ratio between the maximum demand of a system and its total connected load. Since the maximum demand can never exceed the total connected load, the demand factor is always ≤ 1. This property is fundamental to the concept of the demand factor, and it holds true in all practical scenarios.

Important Information

To further understand the analysis, let’s evaluate the other options:

Option 1: It is always greater than 1.

This option is incorrect because the demand factor cannot be greater than 1. The maximum demand of a system cannot exceed its total connected load, as this would imply that the system is operating at a capacity beyond its designed limits, which is not possible.

Option 2: It is always equal to the utilization factor.

This option is incorrect because the demand factor and utilization factor are distinct concepts. The utilization factor refers to the ratio of the actual energy used by a system to the maximum energy it could use over a given period. While both factors are used to assess system efficiency, they measure different aspects of electrical system performance.

Option 4: It is always equal to the diversity factor.

This option is incorrect because the diversity factor is a separate concept from the demand factor. The diversity factor is the ratio of the sum of individual maximum demands of various components of a system to the maximum demand of the entire system. It is used to account for the probability that not all components will operate at their maximum demand simultaneously. Demand factor and diversity factor are related but are not the same.

Option 5: (No content provided for this option in the prompt.)

Conclusion:

The demand factor is an essential metric in electrical engineering, providing critical insights into system efficiency and design optimization. It is always less than or equal to 1, as the maximum demand cannot exceed the total connected load. Understanding this concept helps engineers design systems that are both cost-effective and capable of meeting peak demand requirements without overloading or underutilizing resources.

Concept

The diversity factor is given by:

\(Diversity \space factor={ Sum \space of \space \space individual \space maximum \space demands ​ \over Maximum \space demand \space of \space the \space system}\)

Calculation

Given, Number of apartments = 15

Peak demand per apartment = 8 kW

System maximum demand = 60 kW

Sum of individual demands = 15 × 8 = 120 kW

\(Diversity \space factor={120\over 60}=2\)

Explanation:

Demand Factor

Definition: The demand factor is a crucial term used in electrical engineering that refers to the ratio of the maximum demand of a system to the total connected load of the system. It is a measure that helps in understanding the actual demand on the electrical supply system compared to its full capacity.

Formula: The demand factor is calculated using the following formula:

Demand Factor = (Maximum Demand) / (Connected Load)

Explanation:

The demand factor is important because it provides insights into the utilization of the electrical system. A demand factor less than 1 indicates that the system is not being used to its full capacity. This can happen in residential areas where not all electrical appliances are used simultaneously. Conversely, a demand factor close to 1 indicates that the system is being used near its full capacity, which might be typical in industrial settings where equipment is used continuously.

The calculation of the demand factor helps in designing electrical systems, ensuring that they are neither over-designed nor under-designed. It aids in optimizing the size of electrical components, such as transformers and conductors, leading to cost-effective and efficient electrical system design.

Advantages:

• Helps in efficient electrical system design by indicating actual demand.
• Aids in the optimal sizing of electrical components, reducing costs.
• Ensures the reliability of the electrical supply by preventing overloading.

Disadvantages:

• May not account for future increases in demand if not properly projected.
• Requires accurate measurement and prediction of maximum demand, which can be complex.

Applications: The demand factor is widely used in various applications, including residential, commercial, and industrial electrical system design. It is particularly useful in determining the capacity of transformers, generators, and other electrical equipment.

Correct Option Analysis:

The correct option is:

Option 1: Maximum demand to connected load

This option correctly represents the definition of the demand factor. The demand factor is the ratio of the maximum demand of an electrical system to the connected load of that system. This ratio helps in understanding how much of the connected load is actually being used at peak times, which is crucial for the proper design and operation of electrical systems.

Additional Information

To further understand the analysis, let’s evaluate the other options:

Option 2: Connected load to maximum demand

This option is incorrect as it reverses the ratio. The demand factor is specifically the ratio of maximum demand to connected load, not the other way around. If the connected load is divided by the maximum demand, it would not provide meaningful insights into the utilization of the electrical system.

Option 3: Connected load to average load

This option is also incorrect. The ratio of connected load to average load does not define the demand factor. Instead, this ratio might be used to understand the average utilization of the system, but it does not provide the critical information that the demand factor does, which is the peak demand relative to the system's full capacity.

Option 4: Average load to connected load

This option is incorrect as well. The ratio of average load to connected load does not represent the demand factor. This ratio is more relevant to understanding the overall efficiency and utilization of the electrical system over a period of time, rather than the peak demand compared to the connected load.

Conclusion:

Understanding the demand factor is essential for the efficient and effective design of electrical systems. The demand factor, defined as the ratio of maximum demand to connected load, provides valuable insights into the actual demand placed on the electrical supply system. By correctly analyzing the demand factor, electrical engineers can ensure that systems are neither over-designed nor under-designed, leading to cost savings and reliable operation. Evaluating the other options highlights the importance of accurately defining and calculating the demand factor to achieve optimal electrical system performance.

Demand factor: It is defined as the ratio of maximum demand on the power station to its connected load.

Demand factor = Maximum demand / Total connected load

Demand factor

The demand factor is the ratio of the sum of the maximum demand of a system to the total connected load on the system.

\(Demand \space factor ={Sum \space of \space maximum \space demand \over Total \space connected \space load}\)

The demand factor is always less than 1.

Demand factor for various loads:

1.) Residential load (over 1 kW) = 0.5

2.) Residential load (< 0.25 kW) = Less than 0.5

3.) Motor Load (< 10 HP) = 0.75

4.) Commercial load (for Restaurants) = 0.7

Additional Information Load factor

The load factor is defined as the ratio of the average load to the maximum demand.

\(Load \space factor ={Average \space load \over Maximum \space demand}\)

The load factor is always less than 1.

Diversity factor

It is the ratio of the sum of the individual maximum demands of the various subdivisions of a system to the maximum demand of the whole system.

The diversity factor is always greater than 1.

Concept:  

Demand factor: It is defined as the ratio of maximum demand on the power station to its connected load.

Demand factor = Maximum demand / Total connected load

The value of the demand factor is usually less than 1. It is because maximum demand is always less than the connected load. The knowledge of the demand factor is vital in determining the capacity of the plant equipment.

Calculation:

The  correct  answer is option 4):(time independent quantity)

Concept:

Demand factor (D_f):

It is defined as the ratio of maximum demand on the power station to its connected load.

The value of the demand factor is usually less than 1.

It is because the maximum demand is always less than the connected load.

\(D_f=\frac{MD}{CL}\)

Where,

MD is Maximum Demand

CL is connected load 

Demand factor is taken as a time-independent quantity

Demand factor

The demand factor is the ratio of the sum of the maximum demand of a system to the total connected load on the system.

\(Demand \space factor ={Sum \space of \space maximum \space demand \over Total \space connected \space load}\)

The demand factor is always less than 1.

Demand factor for various loads:

1.) Residential load (over 1 kW) = 0.5

2.) Residential load (< 0.25 kW) = Less than 0.5

3.) Motor Load (< 10 HP) = 0.75

4.) Commercial load (for Restaurants) = 0.7

Additional Information Load factor

The load factor is defined as the ratio of the average load to the maximum demand.

\(Load \space factor ={Average \space load \over Maximum \space demand}\)

The load factor is always less than 1.

Diversity factor

It is the ratio of the sum of the individual maximum demands of the various subdivisions of a system to the maximum demand of the whole system.

The diversity factor is always greater than 1.

Demand factor: It is defined as the ratio of maximum demand on the power station to its connected load.

Demand factor = Maximum demand / Total connected load

Demand Factor

​The demand factor of an electric power station is defined as the ratio of maximum demand on the power station to its connected load.

\(Demand \space factor={Maximum \space demand \over Connected \space demand}\)

The demand factor is always less than or equal to one.

Load Factor

Load factor is defined as the ratio of the average load over a given period to the maximum demand (peak load) occurring in that period.

\(Load \space factor={Average \space demand \over Maximum \space demand}\)

The load factor is always less than or equal to one.

Diversity Factor

The ratio of the sum of individual maximum demands to the maximum demand on the power station is known as a diversity factor.

\(Diversity \space factor={Sum\space of \space individual \space maximum \space demand \over Maximum \space demand}\)

The diversity factor is always greater than one.

Demand Factor (D_F):

The demand factor is taken as a time-independent quantity where the numerator is taken as the maximum demand in the specified time period instead of the averaged or instantaneous demand.

\(D_F=\frac{MD}{CL}\)

Here, MD is the maximum demand
And, CL is connected to load

Calculation:

Here,

We have 15 lights at 100 W each

Hence, Connected load (CL) = 15 × 100 = 1500 W

Given that, only 13 lights are used at the same time.

Hence, the maximum demand will depend on 13 lights.

∴ Maximum demand (MD) = 13 × 100 = 1300 W

⇒ DF = \(\frac{1300}{1500}\) = 0.86 = 86%

The correct answer is option 4):(Maximum demand of a system/Total connected load on the system)

Concept:

Demand factor:

• It is defined as the ratio of maximum demand on the power station to its connected load.
• Demand factor = \(Maximum\: demand \over Total\: connected\:load\)
• The real value of the demand factor is usually less than unity.
• It is because the maximum demand is always less than the connected load.
• The knowledge of the demand factor is vital in determining the capacity of the plant equipment.
• Demand factor varies with time
• The lower the demand factor less system capacity is required to serve the connected load

Demand factor: It is defined as the ratio of maximum demand on the power station to its connected load.

\(D.F.=\frac{MD}{TL}\)

Where,

D.F. = Demand Factor

MD = Maximum Demand

TL = Total connected Load

The value of the demand factor is usually less than 1. It is because maximum demand is always less than the connected load. The knowledge of the demand factor is vital in determining the capacity of the plant equipment.

Application:

We have,

TL = 8 kW

MD = 4 kW

Hence,

DF = 4/8 = 0.5

Demand factor: It is defined as the ratio of maximum demand on the power station to its connected load.

\(D.F.=\frac{MD}{TL}\)

Where,

D.F. = Demand Factor

MD = Maximum Demand

TL = Total connected Load

The value of the demand factor is usually less than 1. It is because maximum demand is always less than the connected load. The knowledge of the demand factor is vital in determining the capacity of the plant equipment.

Additional Information

Utilization factor: It is the ratio of maximum demand on the power station to the rated capacity of the power station.

\(UF=\frac{MD}{RC}\)

Where,

UF = Utilization Factor

MD = Maximum Demand

RC = Rated Capacity

Diversity factor: The ratio of the sum of individual maximum demands to the maximum demand on the power station is known as a diversity factor.

\(DF=\frac{ ∑ ID}{MD}\)

Where,

DF = Diversity Factor

∑ ID = sum of Individual Demands

MD = Maximum Demand 

Plant capacity factor: It is the ratio of actual energy produced to the maximum possible energy that could have been produced during a given period.

\(PCF=\frac{AD}{PC}\)

Where,

PCF = Plant Capacity Factor

AD = Average Demand

PC = Plant Capacity

Demand factor: It is defined as the ratio of maximum demand on the power station to its connected load.

Demand factor = Maximum demand / Total connected load

The value of the demand factor is usually less than 1. It is because maximum demand is always less than the connected load. The knowledge of the demand factor is vital in determining the capacity of the plant equipment.

Important Points

Utilization factor: It is the ratio of maximum demand on the power station to the rated capacity of the power station.

Utilization factor = maximum demand / rated capac

Diversity factor: The ratio of the sum of individual maximum demands to the maximum demand on the power station is known as a diversity factor.

\(Diversity\;factor = \frac{{Sum\;of\;individual\;maximum\;demands}}{{Maximum\;demand\;on\;power\;station}}\)

Plant capacity factor: It is the ratio of actual energy produced to the maximum possible energy that could have been produced during a given period.

\(Plant\;capacity\;factor = \frac{{{\rm{Actual\;energy\;produced}}}}{{Maximum\;energy\;that\;could\;have\;been\;produced}}\)

\( = \frac{{Average\;demand \times T}}{{Plant\;capacity \times 100}}\)

\(= \frac{{Average\;demand}}{{Plant\;capacity}}\)

\(Annual\;plant\;capacity\;factor = \frac{{{\rm{Annual\;kWh\;output}}}}{{Plant\;capacity \times 8760}}\)