Relay setting calculation|Restricted Earth Fault Protection relay Setting Part-2|KNEE POINT VOLTAGE

PART-2
KNEE POINT VOLTAGE, RELAY PICK UP AND STABILIZING RESISTOR CALCULATION FOR REF RELAY SETTING
Two things I should rectify first.
1. By mistake I have said percentage impedance of 8.25 ohm, but percentage impedance is expressed in percentage only, and not by ohm. That has been an unconscious mistake.
2. The formula for calculating the fault current is not completely visible. It shall be (2500/(1.732*0.433*0.0825))
In this video we have explained calculation of knee point voltage, pick up, stabilizing resistor for restricted earth fault relay setting calculation. These calculations are required for successful implementation of Restricted Earth fault protection of alternator and Transformer.
Restricted Earth Fault Protection is also known as differential earth fault protection. It is basically earth fault protection but works on differential relay principle.
Restricted Earth Fault Protection is used to detect earth fault inside a machine in general.
#ElectricalTechnologyAndIndustrialPractice,
#ElectricalEngineering, #ElectricalTechnology,
#RelaySettingCalculation, #REFRelaySetting, #RestrictedEarthFaultProtection
#REF
The explanation given in the video is applicable for all the below mentioned topic.
1. REF Relay setting
2. Restricted Earth Fault relay setting
3. Protection against internal earth fault
4. REF Relay setting calculation.
5. How to calculate settings for restricted earth fault relays
6. Restricted Earth Fault Protection philosophy of relay setting
2. How restricted Earth Fault Protection relay setting is done
3. REF relay setting principle
4. Differential earth fault Protection setting
5. Setting calculation of restricted Earth Fault Protection relay
6. REF relay setting
7. Restricted Earth Fault Protection CT selection
8. REF Protection of Alternator
9. REF protection of transformer
10. Knee point voltage calculation
11. stabilizing resistor calculation
12. high impedance restricted earth fault relay setting
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[@rameshtripathy5978]

It is very much useful for the commissioning engineers !

[@priyal5354]

Vs =60V will appear across secondary terminals of CT, right? How to choose Is?

[@kulkarnir93]

Sir, Thanks for giving such good knowledge about REF protection. How RCT of 4 nos CTs i.e. 3 phase CTs & 1 neutral CT. Also explain the exact method of calculating wire connected with the 4 CTs.

[@yokeleetan8525]

It seems from your calculation Vs is the voltage across the relay and stabilising resistor.

[@thetruelegend2502]

Thanks sir, Crystal clear to understand

[@shantanumajhi5408]

Very Useful

[@elavarashanrajesh6560]

Very usefull sir thank u very much ❤❤❤❤❤

[@surendrakverma555]

Very good. Thanks 🙏🙏🙏🙏

[@mdborhan2690]

very nice

[@jitendradubey3682]

Thanks sir.... Very informative 😊😊😊🙏🙏🙏

[@patelsiddharth7698]

Sir can we use REF protection for 1MVA transformer?

[@jppatnaik2240]

For Each CT whether we consider of One CT (or) all 3 CT ? ( RCT )

[@raviteja-bf8vj]

Say for suppose if the fault has occurred within the Restricted zone and only N CT is seeing the current. In that case say 10 Amps of secondary current has appeared. For that to drive through REF relay coil, a specific voltage will be developed. Since CT is a constant current source if primary current is constant, voltage across CT secondary will vary based on VA burden. If 700 Ohms is being connected as Rstab then to drive 10 Amps of current and 700 Ohms of load, a voltage of 7kV is required. Which in that case metrosil will operate and bypass that as surge. I was not able to understand in normal conditions, when the Rstab is connected, how the current is being flown through relay citing heavy burden.

[@sridhar3377]

Is there any video of this calculation also done for the condition of NCT with resistively grounded??

[@zahidulislam2458]

Nice

[@hzbajlanihzbajlani6699]

We have a factory that requires 6 MVA electric power , Can we use one large transformer and limit the fault current with NGR? our transformer is 11/0.4 KV

[@hplar2972]

Hi,just want to ask you is it earth that was intalled at MSB also the same funtioning?

[@hplar2972]

I mean earth fault relay

[@wongsabarchannel1335]

Do you have Low Impedance REF Calculation Video?

[@bristykhatun2404]

thinks sir vary good job

[@learnbyshiva725]

Thanks sir very good job

[@CartoonwonderlandEdu]

Love u yar ur vedios are so good to understand

[@rakeshnanda9506]

Nyc explanation sir

[@jyothiyecherla7964]

Here RCT Value means combination of 4 cts or one ct?

[@hosseinshabaniroshan8174]

Hi.I want to know exactly how to draw the characteristics of this relay...? Do the differential current and bias current ,which are the necessary characteristics for this relay , come from the normal state of the relay or from fault condition?

[@ajithomas8342]

🎉

[@shankhachongder6065]

Thank you for the video sir

[@balakabimuki2023]

Hello sir, After calculated VS , why should we use the formula of CT Vnee>2Vs?? and here this video you increased the voltage from 120 to 400?????and you told that we can use 650V also..how to choose the maximum voltage ???

[@pceprojectspvt.ltd.6183]

In case the earth fault is inside the zone , how to ensure that insertion of stabilising resistor will not lower the fault current below the pick-up setting of the relay

[@yctsang6561]

I have the same doubt

[@shashah769]

😍😊

[@mdborhun15]

Wow

[@thinkseeeatthroughvickus4555]

Please make a video on - what all relays can be connected from same CT, and where CTs to be installed in case of transformer protection, bus bar protection, so that it wii give an idea how many CTs required

[@thinkseeeatthroughvickus4555]

Can you do a video on PS or PX class CT sizing?

[@ranjan1436]

pls make a video on knee point voltage. so far it is fantastic.

[@electricaltechnologyandind5335]

There is already a voltage on knee point voltage selection. Check the restricted Earth fault protection series

[@wary8113]

WHICH CT RESISTANCE TO BE TAKEN IN CALCULATION? 3 CT OF LINE & 1nct is in parallel?

[@ManojkumarSahoo_electrical]

Sir, How to calculate the power rating (Wattage) of stabilizing Resistor for REF relay.

[@ABHAYSINGH-um3wc]

excellent but please make the more easy those concepts

[@nageshpawar2455]

THANK U VERY MUCH SIR....

[@kameshwarmehta5507]

Fault current calculation how.....

[@ashiqurrhman292]

Nc

[@ashutoshpokhriyal1020]

Sir please share distance protection setting calculations

[@jamesowusu-ansah595]

Sir please, by safely choosing the the knee point of the CT to be twice Vs...Then it's safe to say the LCT's won't get saturated for high value external faults right?

[@electricaltechnologyandind5335]

Yes. That is one of the check point of REF setting

[@jamesowusu-ansah595]

@@electricaltechnologyandind5335 So if it's unlikely to enter saturation by safely selecting your CT knee point, then i really don't see the need of a stabilising resistor Also, won't the stabilising resistor reduce the current in the event of a ground fault within the protected zone, hence, the relay might not operate?

[@electricaltechnologyandind5335]

When vs has occurred that will drive current through relay. For that stabilizing resistance is given. Please watch the video again

[@jamesowusu-ansah595]

@@electricaltechnologyandind5335 But Vs only occurs when the CT'S get saturated right?

[@electricaltechnologyandind5335]

No. When current flows.

[@neerajpiplani185]

Wonderful explanation. Could you please explain why knee votage should be atleast twice Vs

[@shujaatkhan6637]

Dear Sir, Can you please make a video on Knee point voltage

[@mdronvai4405]

❤️🥰😏

[@naimulislam41]

nc

[@akhilsm6840]

Why the CT saturated even though the CT knee point voltage is very high

[@electricaltechnologyandind5335]

Normal protection relay doesn't have high knee point voltage

[@dilipsahusahu680]

Please please please Hindi sir

[@musicvideo1566]

very good

[@sujonshahofficial2572]

Wow