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Calculate the plug setting and the time multiplier setting for a relay to trip in 0.5 seconds with the available data:

- CT Ratio: 400/5
- Normal load current: 380 A
- Overload: 454 A for 25 seconds
- Maximum fault current: 5000 A

Answer :

Answer:

To calculate the plug setting and the time multiplier setting for a relay, we'll use the following information:

CT Ratio: 400/5

Normal load current: 380A

Overload: 454A for 25 seconds

Maximum fault current: 5000A

Desired trip time for fault current: 0.5 seconds

Let's go through the calculations step by step:

Step 1: Calculate Plug Setting Multiplier (PSM)

The plug setting multiplier (PSM) is calculated using the formula:

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PSM=

I

rated

​

I

plug

​

​

Where:

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I

plug

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is the current at which you want the relay to operate (fault current for the desired trip time).

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I

rated

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is the rated current of the relay, which is usually the nominal CT secondary current.

In this case,

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plug

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is the maximum fault current, which is 5000A, and

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rated

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is the CT secondary current at the nominal ratio of 400/5, which is 5A.

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=

5000

5

=

1000

PSM=

5

5000

​

=1000

Step 2: Calculate Time Multiplier Setting (TMS) for Overload

The time multiplier setting (TMS) for the overload condition can be calculated using the formula:

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TMS=

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standard

​

t

desired

​

​

Where:

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t

desired

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is the desired time of operation for the overload condition (25 seconds).

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t

standard

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is a standard time of operation for the relay (usually 1 second).

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25

1

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25

TMS=

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25

​

=25

So, the Time Multiplier Setting (TMS) for the overload condition is 25.

Step 3: Calculate Time Multiplier Setting (TMS) for Fault Current

The time multiplier setting (TMS) for the fault current condition can be calculated using the formula:

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TMS=

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standard

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desired

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×PSM

Where:

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desired

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is the desired time of operation for the fault current condition (0.5 seconds).

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standard

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is a standard time of operation for the relay (usually 1 second).

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PSM is the plug setting multiplier calculated in Step 1 (PSM = 1000).

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=

0.5

1

×

1000

=

500

TMS=

1

0.5

​

×1000=500

So, the Time Multiplier Setting (TMS) for the fault current condition is 500.

Explanation:

To summarize:

Plug Setting Multiplier (PSM): 1000

Time Multiplier Setting (TMS) for Overload: 25

Time Multiplier Setting (TMS) for Fault Current: 500

Please note that relay settings can be influenced by various factors and standards, so it's important to consult with a qualified engineer or follow established guidelines when configuring relay settings for specific applications.

Thanks for taking the time to read Calculate the plug setting and the time multiplier setting for a relay to trip in 0 5 seconds with the available data CT Ratio 400. We hope the insights shared have been valuable and enhanced your understanding of the topic. Don�t hesitate to browse our website for more informative and engaging content!

Rewritten by : Barada

To calculate the plug setting, you divide the overload current by the secondary current (primary current divided by CT ratio). The plug setting is approximately 0.9557. For the time multiplier setting, you'd need data from the IEC time delay curve.

In the scenario you've provided, we're asked to find the plug setting and time multiplier setting.

To begin, to calculate the plug setting, you divide the overload current by the secondary current (which is the primary current divided by CT ratio).

In this instance, the primary current is 380A and the CT ratio is 400/5.

So, you get the secondary current by dividing 380 by (400/5) to get a result of 4.75A.

Subsequently, you get the plug setting by dividing the overload current (454A) by 4.75A, which equals approximately 95.57% or 0.9557 in per unit value.

Now, for the time multiplier setting.

This involves the use of the IEC time delay curve, which, unfortunately, is not provided in this problem. To get an exact value for the time multiplier setting, you would need that specific data in the form of a graph.

However, as stated above, you are trying to achieve an overall operating time of 0.5 seconds, so you would adjust the time multiplier until that setting is achieved as per the curve.

Learn more about the topic of Relay Settings here:

https://brainly.com/question/32142290

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