# How do you calculate earth fault current value by knowing the setting in electromagnetic relay?

Date created: Thu, Jun 3, 2021 6:43 PM

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Those who are looking for an answer to the question «How do you calculate earth fault current value by knowing the setting in electromagnetic relay?» often ask the following questions:

### ❓ How to do relay setting calculation?

Actual time of operation of the relay = (Time obtained from PSM- Operating time graph) * TMS Calculation of PSM Setting: From the figure shown below we can observe that, when the plug position is increasing, the time in seconds is decreasing. An example relay settings shown in the figure below

### ❓ How do you ctmm motor protection relay setting?

Just calculate from motorplate: Watts/(Square3VcosP)=> example motorplate says: 4.7Kw 440V cosP: 0.82 4700W/(square3440V0.82) here you get minimum setting for motor, this case 7.5A JT

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To find the fault current at any point in the network, a sum is made of the impedances in the network between the source of supply (including the source impedance) and the point at which the fault is occurs. To find the fault current Ik, the nominal applied voltage, U0 is divided by the summed impedance Z.

From current setting we calculate the trick current of the relay. Say current setting of the relay is 150 % therefore pick up current of the relay is 1 × 150% = 1.5 A. Step-3 Now we have to calculate PSM for the specified faulty current level. For that, we have to first divide primary faulty current by CT ratio to get relay faulty current.

(2) For Short Circuit Protection (Magnetic Setting): (C) Short Time pickup Current Setting (Im): Short time protection is time-independent. It is determines or sets the level of fault current at which the short-time trip delay countdown is actuated. Short Time Pick up Value (Im) (multiplied by the ampere rating) sets the short circuit current level…

There are many programs to determine the available fault current at a given location but most just provide the final AFC value, not the math to back it up. What would be the available fault current at the service if the service entrance conductors are only 80 feet instead of 95?

PSM and TMS settings that is Plug Setting Multiplier and Time Multiplier Setting are the settings of a relay used to specify its tripping limits. To understand this concept easily, it is better to know about settings of the Electromechanical Relays. If we clear the concept for these relays first then understanding the Numerical Relay settings becomes easy.

Required Over Load Relay Plug Setting = 480 / 600 = 0.8. Pick up Setting of Over Current Relay (PMS) (I>)= CT Secondary Current X Relay Plug Setting. Pick up Setting of Over Current Relay (PMS) (I>)= 1 X 0.8 = 0.8 Amp. Plug Setting Multiplier (PSM) = Min. Feeder Fault Current / (PMS X (CT Pri.

• NEC® 110.10 Circuit Impedance, Short-Circuit Current Ratings, and Other Characteristics. • Requires the equipment to have a short circuit current rating not less than the maximum available fault current. • The maximum fault current must be calculated and varies based on system size/location. • Similar Requirements in OSHA 1910.303(b)(5)

This is basically a combination of the steps in the per-unit calculation method: Step 1: Calculate the per unit fault current: $$I_{fault-pu}= \dfrac{1}{Z_{pu}}$$ Note that $$Z_{pu} = \dfrac {Z_{\%} }{100}$$ Step 2: Calculate the nominal base current: $$I_{nominal-base}= \dfrac{S_r}{\sqrt{3} \times U_r}$$ Step 3: Calculate the actual fault current:

If air-compressor still running :-. 1) check your overload relay condition.Perform test trip to ensure it is function properly,if not change it. 2) Check your Full Load Ampere using Clamp on meter for actual value and compare with your setting. If your compressor always trip :-.

Current Value The JEM 1357 standard (Inductive and Static Protective Relays for Three-phase Inductive Motors) stipulates that the must operate value should fall between 105% and 125% of the current SV and the majority of Motor Protective Relay manufacturers conform to this standard. This value is sufficient for any motors unless otherwise specified.

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### How do you calculate total current for 1000kva transformer?

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### When human body shocked by current burry in earth?

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