Motor protection relay setting calculation excel

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Motor protection relay setting calculation excel

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motor protection relay setting calculation excel

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Up to date with Schneider Electric Low Voltage protection devices and circuit breakers. To design an installation when searching information on protection settings and time current curves. To design an installation where continuity of supply is required.

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To optimise the installation cost. To generate cables schedule and choose proper cable size, for greater system reliability. To determine the cross section area of the cable during installation. When dealing with an extension of an existing installation, or with a load upgrade: To set the new protection and to see the result on the time current curve. To set the new protection taking into account protection discrimination and optimise the cost of the extension.

To select circuit-breakers taking into account discrimination. To verify whether the existing cable is adequate. To calculate cable size and to assist engineers during project expansion. You are a panel builder, Electrical calculation tools can help you: To preset protection trip unit and to display the result on the time current curve. To preset protection trip curves when protection discrimination is mandatory. To select new circuit-breakers when discrimination is mandatory.

To optimise the cost of the switchboard thanks to protection coordination. To identify the losses in existing installation. To re-design of the electrical network system. To understand root causes and to solve the issue: When facing a protection tripping issue. When facing a protection coordination issue.

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Need help?Overload relay is the one of important device for motor control. It can prevent our motor from overheat or winding burning due overload of ampere. We need to setting the value of overload relay properly depend on our application and motor full load ampere.

If we setting low from FLA,it can cause motor trip c0ntinues and process not running smoothly. But if we setting to high from FLA,the overload relay cannot protect the motor if overload happen. It can cause the motor failure or winding burns. So we must calculated and get a right setting for the overload relay. For adjustable protective devices, In corresponds to the value set.

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But it is depend on operation and functional of motor. For more detail setting,please refer manual guide of motor from manufacture. We also can setting overload relay value depend on value of service factor motor. Example if service factor 1.

Normally,overload relay have this 2 reset function selection. We can choose manual or automatic reset after it trigger overload from motor.

motor protection relay setting calculation excel

I recommended for manual reset function because we can know when it trip and we can troubleshooting the root cause for tripping issue. So after we found the root cause,we can reset back the overload relay and can continue the operation.

I will give you one answer please check whether thwt is correct or not? While increasing the relay setting of the air circuit breaker no need to switch off the circuit breaker. If we want to decrease the relay setting means we have to switch of the circuit breaker is it correct if this is wrongmeans plese give me correct idea and what is the actual reason and correct answer.

Regards Gopalthulasidoss. I was wondering why my overload relay in an air compressor with a star delta starter is downsized compared to the motor fla?Differential Protective Relay is a protective relay that functions on a percentage or phase angle or other quantitative difference of two currents.

As long as the current flow through the protected component is unchanged in magnitude and phase, the relay does not pick up. Such a condition would occur for a short-circuit fault outside the zone of relay protection. The example differential protection relay shown in the below figure is a transformer differential relay.

The following protection functions are used in this relay. Before going through bias differential settings, below settings are needed to specify when there are no interposing CTs used in the circuit.

Line CTs are used to measure fundamental frequency currents. These line currents need to vector corrected before applying to the differential elements. The multiplier is used to correct any CT ratio mismatch so that ideally nominal current is applied to the biased differential algorithm. ICT Vector setting applies the correct vector compensation to the current applied to the differential algorithm. Means the phase change introduced due to transformer connections is nullified using this setting.

Magnitude restraint bias is used to ensure the relay is stable when the transformer is carrying load current and during the passage of through out of zone fault current.

This is the minimum level of differential current at which the relay will operate. This setting is used at low levels of load to prevent operation of differential relay due to OLTC tap positions. Typically this setting is chosen to match the on load tap-change range. With increasing load the differential current required for operation should increase to ensure stability.

In case of through fault or increased loads, the unbalance currents due to OLTC tap position, relay tolerance and CT measurement errors also increase. To prevent operation of the relay due to these unbalance currents the bias setting need to increase. This setting is expressed in the slope form.

The bias slope expresses the current to operate the relay relative to the biasing restraint current. The Bias slope setting chosen must be greater than the maximum unbalance, it is selected to ensure stability when through fault or heavy load current flows in the transformer and the tap changer is in its extreme position.

This setting is primarily needed to prevent operation of relay in case of through fault results saturation of CTs causes a transient differential current to be detected by the relay.

The bias slope limit is chosen to ensure the biased differential function is stable for high through fault currents coincident with CT saturation. These settings are chosen to ensure the biased differential function is stable for further high through fault currents coincident with CT saturation. Harmonic bias is used to prevent relay operation during magnetizing inrush current into one winding when the transformer is first energized. The magnetizing Inrush detector operates when the second harmonic current exceeds a set percentage of the fundamental current.

relay setting calculation excel

This setting can be used to prevent operation of the 87BD elements in the presence of allowable over-fluxing conditions. The 87HS element is generally applied as an unrestrained differential element to provide fast tripping for heavy internal faults. REF is more sensitive than overall biased differential protection 87BD to earth faults it can protect against faults for a greater portion of the transformer windings or where the impedance in the earth fault path is relatively high.

For a solidly earthed star winding, the REF function is roughly twice as sensitive in detecting a winding earth fault, than biased differential protection. Restricted Earth Fault Protection in detail explained in previous post. If the earth is dry it is difficult to make an effective short circuit to earth. The resulting earth fault current limited to very low levels.October 11, 43 Comments. Filed under Uncategorized. About Jignesh. Parmar B.

Tech Power System ControlB. E Electrical. Membership No:M He is Presently associate with one of the leading business group as a Deputy Manager at Ahmedabad,India.

Since it is energy it is always consist of Power P which equal with current I and consist of t time.

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Whereas high over current setting is to limit short circuit withstand. Setting high over current setting shall be wise to distinguish between real short circuit and starting current. Hello sir, I am not clear with this explanation, can you explain with some example.

But i have noticed that at some places SQ. Does HT cable selection is related with fault level and HT cable at 11 kv should not be used less than Sq. For HT Cable one important criteria which need to be consider is Short circuit level. Normally 11KV S. C level is 20 to 25KA at it varies according to Electricity provider company.

C falls in 17 to 20KA. For HT cable you have to consider S. C level of utility first than Current carry capacity of Cable. Please let me know the details of selection of Neutral grounding resistance. Your suggestion please. Dear K. F is better to make it less or equal 1 ,it means always lagging. We are going to synchronize 30MW,11kv DG with this grid breaker. Power failure time, I wish to isolate grid feeder. Please advice. Sir, thank u for your notes on Normally inverse curve.

By the same way plz give the formula for Extermly inverse curve. You may assume any capacity of transformer installed in the outgoing feeder in above example. Sir, I would like to known how relay can be wiried and implemented and settings and how its configured in relay panel.Inadvertent shutdown because of human mistake or motor protection maloperation Motor failure Load failure. Removal and Installation. Loss of Production. Setting of the motor protection relay is based on the motor datasheets information and system configuration.

Datasheets are normally provided by motor manufacturer. System configuration data can be obtained from single line diagram. Thermal Modeling: Motor Thermal Limits Curves The motor thermal limits curves consist of three distinct segments which are based on the three running conditions of the motor: The locked rotor or stall condition.

Ideally, curves have been Motor acceleration. A hot motor is defined as one that has been running for a period of time at full load such that the stator and rotor temperatures have settled at their rated temperature.

motor protection relay setting calculation excel

Conversely, a cold motor is defined as a motor that has been stopped for a period of time such that the rotor and stator temperatures have settled at ambient temperature. For most motors, the motor thermal limits are formed into one smooth homogeneous curve. Thermal Modeling: Motor Thermal Limits Curves The acceleration curves are an indication of the amount of current and associated time for the motor to accelerate from a stop condition to a normal running condition.

As can be seen on the curve shown, since the voltage and current are lower, it takes longer for the motor to start. Therefore starting the motor on a weak system can result in voltage depression, providing the same effect as a soft-start. Motor Specifications Horsepower: Engineering unit of power 33, lb 1ft in 1 min. Motor Specifications Efficiency: An indication of how much electrical energy is converted to output shaft mechanical energy expressed as a percentage.

Thermal Model. Motor Specifications Service Factor: When the voltage and frequency are maintained at the values specified on the nameplate, the motor may be overloaded up to the horsepower obtained by multiplying the nameplate horsepower by the service factor. At the service factor load greater than 1.

But the locked rotor current and breakdown torque will remain the same. For a given insulation, motors with a 1. This allows the motor to operate close to the service factor without exceeding rated temperature limits of the insulation. This will shorten the life expectancy considerably. Insulation lifetime decreases by half if motor operating temperature exceeds thermal limit by 10C. These motors are classified as rotor limited.

Motor current must increase to the level higher than overload pickup within 1 second otherwise motor algorithm will declare the Running state. Thermal Modeling The primary motor protective element of the motor protection relay is the thermal overload element and this is accomplished through motor thermal image modeling.

Overload relay setting and calculation

This model must account for thermal process in the motor while motor is starting, running at normal load, running overloaded and stopped. Algorithm of the thermal model integrates both stator and rotor heating into a single model. Thermal Modeling If the motor has been designed conservatively, the portion of the acceleration curve under the motor thermal limits curve is less than a third to a half in terms of trip time, and the motor has been applied conservatively during acceleration or running the acceleration and thermal limits curve do not cross then thermal model settings can be set easily.This section is dedicated to tools every electrical engineer can use in daily work.

These spreadsheets below will make your job much more easier, alowing you to shorten the time used for endless calculations of cables, voltage drop, various selections of circuit breakers, capacitors, cable size and so on. Spreadsheets are mostly developed by expirienced electrical engineers and programmers thank you mr. Jignesh Parmar! They all really did an awesome job, you must admit! With above settings, can anybody suggest why incomer feeder tripped during outgoing feeder cable fault?

Although I am not an electrical engineer but an electronics on I appriciate your contribution. Some subjects are very similar between the two careers. I have downloaded a few of the spreadsheet. They are so helpful. Can you please make one for vector group calculations. It must be able to draw the grouping as you put the figures on the spreadsheet. It would be a more useful spreadsheet if you can actually size the loads for a residential home.

Thanks, John. Dear Sir, we need a Dc cable Calculator for find out the size of cable for varies DC motor or invertor.

Motor Protection Relay Setting Guide

I am requested to prepare excel sheet for calculating per unit value for common base particularly MVA base for transformer, transmission line for all conductors. Thank You very much. Your article is of great help to me as an electrical engineer. It will surely boost my electrical strength. These sheets are fabulous. An ample list of topics for calculations have been covered.

It shall of great use to electrical engineer. I have found a lot of valuable spreadsheets on your portal. Would you please confirm me that upto which extent these spread sheets are correct so that I may apply these spread sheets directly to my practical field work with percent of mind satisfaction. Hi team, if there is any shortcuts or easy methods in testing commissioning,and how can reduce the commissioning time for particular tests.

Thank you so much for such a great files. Great effort to organize EE info at one place, future target should be to evolve projects group. Secondly, I have checked all the Excel sheets, I saw that most of them were protected, so I could not see the formulas, which I want to recheck.

Can you help me to unlock them?? These excel worksheets are very useful for design engineers. Thank you for sharing free of cost on purpose knowledge for everyone. Thanks a lot this is a great help for professionals and trainers.

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A real quality work with lots of consideration for fellow professionals in the stream. Once again Thank you very much. Dear EEP Team, you are doing a wonderful job by making available such calculations for every day use by practicing engineering professionals, cs nambisan. Do you know anything about those languages? They are all completely different. I suggest you research a little bit before asking a question like this.

motor protection relay setting calculation excel

Hello sir, I want to know that, is there any calculation table for transformer firewall protection? Please I like to calculate the required number of earth rods for substation mat specially in the preimeter Thanks in advance.The majority of winding failures in motor are either indirectly or directly caused by overloading either prolonged or cyclicoperation on unbalanced supply voltage, or single phasing, which all lead through excessive heating to the deterioration of the winding insulation until an electrical fault occurs.

As an electrical machine has a relatively large heat storage capacity, it follows that infrequent overloads of short duration may not adversely affect the machine. However, sustained overloads of only a few percent may result in premature ageing and insulation failure. Furthermore, the thermal withstand capability of the motor is affected by heating in the winding prior to a fault.

A generic mathematical model that is accurate is therefore impossible to create. However, it is possible to develop an approximate model if it is assumed that the motor is a homogeneous body, creating and dissipating heat at a rate proportional to temperature rise.

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SIR what is about dc motor protection? My question is 1 is the overload setting too high? Can I say minimum value of overload setting cannot lower than Thermal overload protection Ir can be adjusted in amps from 0.

This actually depends on the manufacturer. Your example shows that circuit breaker is over dimensioned. CB should be at least A breaker with Ir set to 0,4. Please let me know. Thanks and regards. Search for:. Premium Membership. More Information. Thermal Overload Motor Relay Protection. Winding failures in motor The majority of winding failures in motor are either indirectly or directly caused by overloading either prolonged or cyclicoperation on unbalanced supply voltage, or single phasing, which all lead through excessive heating to the deterioration of the winding insulation until an electrical fault occurs.

The variety of motor designs, diverse applications, variety of possible abnormal operating conditions and resulting modes of failure result in a complex thermal relationship. Related EEP's content with sponsored links. It helps you to shape up your technical skills in your everyday life as an electrical engineer.

Professional in AutoCAD programming. Mohammad Hasan kalantari Jan 22, Edvard Nov 30, Leave a Comment Cancel Reply. Subscribe to Weekly Digest Get email alert whenever we publish new electrical guides and articles. The content is copyrighted to EEP and may not be reproduced on other websites.

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