Question 1

What is the definition of ANSI 67N/67NC - Directional earth fault?

Accepted Answer

Earth fault protection, with selective tripping according to fault current direction.3 types of operation: type 1: the protection function uses the projection of the I0 vectortype 2: the protection function uses the I0 vector magnitude with half-plane tripping zonetype 3: the protection function uses the I0 vector magnitude with angular sector tripping zone ANSI 67N/67NC type 1 Directional earth fault protection for impedant, isolated or compensated neutral systems, based on the projection of measured residual currentANSI 67N/67NC type 2 Directional overcurrent protection for impedance and solidly earthed systems, based on measured or calculated residual current.It comprises an earth fault function associated with direction detection, and picks up if the earth fault function in the chosen direction (line or busbar) is activated.ANSI 67N/67NC type 3 Directional overcurrent protection for distribution networks in which the neutral earthing system varies according to the operating mode, based on measured residual current.It comprises an earth fault function associated with direction detection (angular sector tripping zone defined by 2 adjustable angles), and picks up if the earth fault function in the chosen direction (line or busbar) is activated.This protection function complies with the CEI 0-16 Italian specification.

Question 2

What is the Power budget for AS, AS-P and IO modules?

Accepted Answer

PS-24V is the power supply for the SmartX AS-P servers, Automation Server, and I/O modules. The PS-24V power supply requires an input voltage of either 24 VAC +/–20 % or 24–30 VDC. Use the power budget to calculate the maximum number of devices that the power supply, PS-24V, can supply. If more devices are used, additional power supplies must be added to the I/O bus. The power supply delivers and output voltage of 24 VDC +/– 1 V at an output current of about 1.25 A. The power supply can supply power for loads up to 30 W.To determine the number and position of the power supplies, use the following power budget table.

Question 3

What are the requirements of SEMI F47 that products tolerate in case of voltage sags?

Accepted Answer

SEMI F47 requires that products tolerate the following voltage sags: 50% remaining voltage, 50% missing voltage, for 200 milliseconds70% remaining voltage, 30% missing voltage, for 500 milliseconds80% remaining voltage, 20% missing voltage for one second.

Question 4

What is the difference between In-line and Inside Delta Soft Starter Circuits?

Accepted Answer

The Altistart 48 connected in the motor supply lineThe motor connection depends on the supply voltage, which in this example is a star connection.The motor connection depends on the supply voltage, which in this example is a delta connection.The Altistart 48 connected in the motor delta windingATS48***Q or ATS48***YS316 starters connected to motors with delta connections can be inserted in series in the motor windings. They are powered by a current which is less than the line current by a factor of SQRT 3, which enables a starter with a lower rating to be used.

Question 5

Can we control circuit breaker through wifi?

Accepted Answer

We can only control On and OFF through isc (which is connected to router Which has wifi )please check more information through the link belowhttp://www.schneider-electric.com/en/product-range/62072-enerlin-x-com-x/

Question 6

What is meant by vector group for transformers and why is it important?

Accepted Answer

What is vector group for transformers?A vector group is the International Electrotechnical Commission (IEC) method of categorizing the high voltage (HV) windings and low voltage (LV) winding configurations of three-phase transformers.The vector group designation indicates the windings configurations and the difference in phase angle between them.Example: a wye HV winding and delta LV winding with a 30-degree lead is denoted as "Yd11".Common vector group presentations are tabulated below. Why is the vector group important to specify? As different combinations of winding connections will result in different phase angles between the voltages on the windings, transformers connected in parallel must have the same vector group because the mismatching of phase angles will result in circulating current and other system disturbances.

Question 7

what is the Installation guide for RCCB for 3P without neutral ?

Accepted Answer

Please refer the attached document connection in 3P RCCB.You can follow the same document for connection in three-Phase without neutral.>> If you are using Acti9 range RCCB, You don't need to add the resistor with iID Acti9 RCCB. You can directly connect the 3 phase on 3 poles of RCCB (without neutral).>> If you are using the Multi9 ID range RCCB, we need to add a resistance with specific resistance values to be compliant with 380-415V. Please refer the attached sheet for connection & resistance values to e used with multi9 range of RCCB.The devices have a toroid which gets energized on out of balance currents and trips .The toroid does not care if there is 2 or 3 or 4 lines connected to it as far as out of balance current is concerned.If there is 3 phases + N then all the phases and N conductors will vector sum to zero - unless there is out of balance current = trip if exceeding the threshold..If there is 3 phases and No N conductor - then exactly the same applies = sum of the 3 currents = zero or you have a trip condition if the out of balance current is greater than the threshold.We can get by without having a N conductor connected to the RCCB as below - because the test button creates a resistive load outside the toroid at rated voltage to test trip the device.

Question 8

What are differences in forms 1,2,3,4 for IEC standards ?

Accepted Answer

Attached extract from IEC61439-2 describing the type of forms.

Question 9

What is meant by Symmetrical and Asymmetrical breaking currents?

Accepted Answer

issue:Customer wants to know the value of the symmetrical and asymmetrical breaking current of the circuit breaker and what do they mean.Environment:Circuit Breaker Resolution:- Symmetrical breaking current is the RMS value of AC component of short circuit current at the instant of separation of the contacts. It does not take into account the DC offset.- Asymmetrical breaking current is is the RMS value of the combined sum of the DC and AC components of the short circuit current at the instant of separation of the breaker contacts. This DC offset is of decaying nature which is dictated by the time constant of the system. As shown in the above picture the DC offset decays in a few cycles and is left only with the symmetrical component. Hence if a breaker has to close before the DC component decays, then the breaker’s breaking capacity is to be calculated for the asymmetrical current at the time of breaking.

Question 10

What is the selection criterion of Circuit Breakers for the Capacitor bank application.

Accepted Answer

The selection should be done after derating the Circuit Breaker taking into consideration voltage variation and capacitors tolerances that could increase nominal current up to 1.5In. The Derating factor of 1.5In Where In = Q/ ( Square root of 3 ) Un Q = Capacitor Power Un = Nominal Voltage Choose the Micrologic with delay time selection, so that the Circuit Breaker does not trip due to initial high inrush current. Also to be taken into account are the parameters like supply frequency, operating voltage & harmonics level of the power system for such application. Refer the attached sheet for further details for selection of Circuit Breaker for Capacitor duty application. Note: Use the phase barrier between the phases in Circuit Breaker to prevent flashover due to heavy inrush current.

Question 11

In a 3 phase system, why does the meter still show voltage reading on one of the phases even after breaking the phase circuit?

Accepted Answer

Issue:Testing phase loss on a meter doesn't result in a null voltage reading.Environmnet:EasyLogic Series Power MetersPowerLogic Series Power MetersResolution:The voltage seen is what we call "phantom voltage", its a known phenomenon with all high impedance power meters. These phantom voltages are normal artifacts of the design and should not pose any safety concerns to the end user.In some cases it'll probably disappear by power cycling the meter. Most power meters are not designed to monitor phase loss, as it'll always assume the presence of the 3 phases and the neutral, depending on your parameters setup. External devices are used to detect such occurrences, like phase control relays.

Question 12

Why is Neutral and Earth (Ground) Connection forbidden Downstream from Main Panel?

Accepted Answer

The question is often asked what is the maximum voltage permitted between the Neutral and Earth (Ground) conductor and if the Neutral and Earth can be bridged to achieve a zero value.This can be a difficult topic, in fact in many cases it can be dangerous. As you will see from the attached document, there are many reasons why it is not allowed.

Question 13

Which RL(lead resistance from CT to relay) is to be used in Knee Voltage calculation if Current Transformers (CTs) used in High Impedance Restricted Earth Fault are at different distances from relay?

Accepted Answer

Issue:Having two different values for RL ( Lead resistance from the CT to the relay); RL from the phase CT to the relay and RL from the neutral point CT to the relayEnvironment:Protection Function ANSI 64refHigh impedance differentialSepam 80 Current Transformer requirementResolution:In any application where the high impedance differential is used, all the CTs must have the following:- the same ratio,- the same magnetizing curve (same minimum Vk),- the same maximum Rct (current Transformer secondary winding resistance),- if the relevant CTs are not at the same distance from the relay, take the maximum RL.Attached Cahier Technique no.194 for more information about high impedance calculation

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