What is the current for both motors. Overload Relay Range . You only need to choose one size of supply cable to the motor starter. Min Thermal Over Load Relay setting =70%x7= 5 Amp, Max Thermal Over Load Relay setting =120%x7= 9 Amp. With a star/delta system of operation each of the six cores going to the windings carries 58% of the full load current ie 22 amps approx. Star Delta Starter The Star Delta Starter is a very common type of starter and is used extensively as compared to the other type of starting methods of the induction motor. 4 AMP. Every Cable is unique in its appearance, utility and even performance. mm Al. question: a three phase delta connected motor draws a line current of 18A∠-85 degree from the 400v supply. Basic Calculation of Motor Torque… On Sat, Sep 1, 2018 at 12:44 AM Electrical Notes & Articles wrote: How to calculate the size of power contactor /fuse/over load relay/power cable size for DOL Starter. that should be 35,60,100% for star delta and main the main contactor makes in star but breaks FLA can't recall if they're sized that way in practice-i assume so the overload in series with the motor windings gives the closest protection folowed by supply lines and delta ( Log Out / I think you would need two overload relays, one for Delta contactor, and one for the Star contactor It's not the way i've always done it. P352 = calculated or measured per-phase value for the cable resistance. The content in electricalnotes.wordpress.com is for personal, non-commercial use only. IET Services Limited is registered in England Registered Office Savoy Place, London, WC2R 0BL Registration Number 909719, IET Services Limited is trading as a subsidiary of the Institution of Engineering and Technology, which is registered as a Charity in England & Wales (no 211014) and Scotland (no SC038698). If overload is placed after the Point where the wiring Split into main and delta Contactor, Size of over load relay at 58% (1/1.732) of the motor Full Load Current because we use 6 leads going to the motor, and only 58% of the current goes through the main set of conductors (connected to the main contactor). I work on the basis that the line current is the figure to use for cable sizing. For detail about star delta stater please read my last […] Top: Bottom. Size Supply Side . Maximum Locked Rotor Current =1000x10x3.14/1.732×415=44 Amp. Hence the cable rating formula can be written as, Cable size = 1.5 x Full Load Current. AMP. You must size the short-circuit ground-fault protection device from 150% to 300% of the motor FLC [Table 430.52]. He has published numbers of Technical Articles in “Electrical Mirror”, “Electrical India”, “Lighting India”,”Smart Energy”, “Industrial Electrix”(Australian Power Publications) Magazines. This value is the same for a star or delta connected motor, since the delta connection of the motor does not influence the cable resistance. There are two contactors that are close during run, often referred to as the main contractor and the delta contactor. He is Freelancer Programmer of Advance Excel and design useful Excel base Electrical Programs as per IS, NEC, IEC,IEEE codes. Size of Main Contactor =58%x13 = 8 Amp. Also > Calculate Size of Overload Relay if O/L Relay Put in the” >. Max. Thickness of the cable is directly proportional to the ampere rating.. Just divide the kW by rated supply voltage you can determine the operating current by seeing that we can determine the thickness of the wire.. [Image source : Google image ] … For both DOL and Star-Delta Starter input fields are: System Voltage (V) Phase (1ph/3ph) Type of Motor (single phase, 3-phase induction, synchronous, wound rotor etc.) He is Freelancer Programmer of Advance Excel and design useful Excel base Electrical Programs as per IS, NEC, IEC,IEEE codes. Easy way to calculate motor torque, fuse, CB, OL relay and contactor. For motors rated 40EC with a Service Factor of 1.15 or greater, 125% of the motors FLA is used to calculate the maximum size device for overload protection. He is member of Institution of Engineers (MIE) and CEng,India. straw. FuseTalk Standard Edition v3.2 - © 1999-2020 FuseTalk Inc. All rights reserved. Motor wire size and circuit protection calculator. Just to avoid confusion there is a Jaymac and a Jaymack involved in this discussion!! Hi .This video shows how to calculate cable and circuit breaker (fuse)for the design current. Cable length = 200 m. Load Current = P / (1.732 x V x Pf x Eff) —> (P = √3 x Vx I CosΦ = for three phase circuits) = 125000 / (1.732 x 415 x 0.8 x 0.94) ~ 230 A. 12 Comments. Fill in your details below or click an icon to log in: You are commenting using your WordPress.com account. Membership No:F-1264873 ,M-1473586.He has more than 19 years experience in Transmission -Distribution-Electrical Energy theft detection-Electrical Maintenance-Electrical Projects (Planning-Designing-Technical Review-coordination -Execution). Non-Inductive or Slightly Inductive ,Resistive Load, Switching of Electrical Incandescent Lamp, Slightly Inductive Load in Household or same type load, Hermetic refrigerant Compressor Motor with Manual O/L Reset, Hermetic refrigerant Compressor Motor with Auto O/L Reset, Control of Restive & Solid State Load with opto coupler Isolation, Control of Restive Load and Solid State with T/C Isolation, Control of Small Electro Magnetic Load ( <72VA), Control of Small Electro Magnetic Load ( >72VA). August 31, 2018 MM Al 1.5 Sq. But dont forget, as someone as already said the correction factors. Change ), You are commenting using your Facebook account. ( Log Out / The efficiency of the motor and the machine it drives we must again assume are adequate for the end result. Thermal over Load Relay setting =100%x13= 13 Amp, Disadvantage: O/L Relay will not give Protection while Motor runs in Delta (Relay Setting is too High for Delta Winding). Can you please clarify that even as per type 2 for MPCB or MCCB i.e. I am assuming the topic we are discussing is in the UK or Ireland and that the power supply in question is 400/415 volt 3 phase 50hz and that the motor is compatable with the power supply. Direct Online Starter. Hi, were upgrading a motor at work from 11kw to 18.5kw. I would like to know about the selection of cable for motors. The Main and Delta contactors are smaller compared to single contactor used in a Direct on Line starter because they Main and Delta contactors in star delta starter are controlling winding currents only. i have a question about three phase power. Size of Star Contactor =33%x13 = 4 Amp. Maintained by Rudra Softwares www.rudrasoftwares.net Z. i don’t understand why. Change ), You are commenting using your Twitter account. This transformer calculator helps you to quickly and easily calculate the primary and secondary full-load currents of the transformer. Maximum Size of Time Delay Fuse =300%x13= 39 Amp. Post was not sent - check your email addresses! About Jignesh.Parmar (B.E,Mtech,MIE,FIE,CEng)Jignesh Parmar has completed M.Tech (Power System Control), B.E(Electrical). Today, we are here with another comprehensive Copper and aluminum wire size calculator As we have discussed in detail the topic of “How to calculate the proper wire size for Electrical Wiring. Sq. Tridonic are currently recruiting for a Hardware Engineer to join the business in Spennymoor. The currents in the six conductors will be I (line) for the star connection, so 8.9A. And relation between them what is the ratio of between them?? This is the full load current cable needs to cater in Ideal condition. Max. you can not reproduce,republish or communicate any of the content , including files downloadable from this website, without the permission of the copyright owner.The use of this content on any other websites breaches copyright Act. Sharing Abstracts,Notes on various Electrical Engineering Topics. The setting must be x0.58 FLC (line current). In star connection at start, the motor draws and delivers 1/3 of its full rated power. fuseless what will be the standard for contractor sizing, will it follow the same thumb rule of 58% and 33%? For the delta connection the currents are I (phase) so. He wants to Share his experience & Knowledge and help technical enthusiasts to find suitable solutions and updating themselves on various Engineering Topics. Calculate Size of each Part of Star-Delta starter for 10HP, 415 Volt Three Phase Induction Motor having Non Inductive Type Load, Code A, Motor efficiency 80%, Motor RPM 600, Power Factor 0.8. please share short circuit calculation ( base KVA method) in excel format. I (phase) = I (line) / root (3) = 26.7 / 1.732 = 15.42A. Star contactor can be selected smaller than the others, providing the star contactor pulls first before the main contactor. He is FIE ,MIE and CEng from Institution of Engineers,India. Recommended Cable . Thank you very much sir, Electrical notes shared are very useful. please can you explain why? Disadvantage: We must use separate short-circuit and overload protections. The calculation of current does not depend on the rpm you just need hp and voltage. Motor Full Load Current (Line) = (10×0.746)x1000/1.732×415=13 Amp. On Sat, 1 Sep 2018, 00:14 Electrical Notes & Articles, wrote: > Jignesh.Parmar posted: ” Calculate Size of each Part of Star-Delta starter > for 10HP, 415 Volt Three Phase Induction Motor having Non Inductive Type > Load, Code A, Motor efficiency 80%, Motor RPM 600, Power Factor 0.8. AMP. Line 1 AMP. He has published numbers of Technical Articles in “Electrical Mirror”, “Electrical India”, “Lighting India”,”Smart Energy”, “Industrial Electrix”(Australian Power Publications) Magazines. Jun 25, 2006 #1 i am a student. Overload Relay Range . You have 400A rather than 400V in your equation. System Voltage, V1 = 415. My first post was simply presenting the basic principles for the three phase circuit - which is all I intended to do. Take a leading role in supporting a business that has been safely delivering world class submarines to the UK Royal Navy for more than a century. Motor Rated Torque (Full Load Torque)=5252x10x600=88 lb-ft. Motor Rated Torque (Full Load Torque)=9500x(10×0.746)x600 =119 Nm. RECOMMENDED CABLE SIZES FOR MOTORS; CURRENT RATING OF WIRES & CABLES; Motor Output Clear. AMP. Making/Breaking Capacity of Contactor=1.5×13= 19 Amp. Backup Fuse (max.) He is Presently associate with one of the leading business group as a Deputy Manager at Ahmedabad,India. A good field reference for maintenance and troubleshooting is Ugly's Electric Motor and Controls (Ugly's Electric Motors And Controls, 2014 Edition).This calculator is based on information found in this reference guide, and can help electricians troubleshoot maintenance and control circuits. Joined Jun 25, 2006 1. I tend to look at an 18.5 kw motor as drawing approx 37 amps /phase. Motor Full Load Current (Phase) ==13/1.732=7 Amp. Normally fit one overload (usually on the LINE or MAIN contactor) and normally rate at 0.58 of the FLC. Membership No:M-1473586.He has more than 16 years experience in Transmission -Distribution-Electrical Energy theft detection-Electrical Maintenance-Electrical Projects (Planning-Designing-Technical Review-coordination -Execution). 415 V 3Ph 50Hz. © 2020 The Institution of Engineering and Technology. As the starting current is very high and if we select the cable on full load amps so can it bear the high inrush current? Please càn you enlight me on those figures, 9500,5252 ànd 13 where you got them from!thanks, How to calculate the amps of a motor if in star and delta. MM Cu. Kidblue. If Over Load Relay supply the entire motor circuit and are located ahead of where the power splits to the Delta and Star contactors, so O/L Relay size must be based upon the entire motor Full Load Current. The connection of a three-phase induction motor with a star delta starter is shown in the figure below. Second motor is 5hp,3phase,50hz,3000rpm. ( Log Out / Sorry, your blog cannot share posts by email. Sq. This site uses Akismet to reduce spam. As per above chart Minimum Locked Rotor Current =1000x10x1/1.732×415=14 Amp. Star Delta Starter. Describes cable resistance between inverter and motor for one phase (see Parameterlist). The current in each of the six cables from the star/delta starter to the motor will be 58% of the line current. Motor KW = 125. Kindly let me know. May 5th, 2007, 03:00 AM. Maximum Size of Instantaneous Trip Circuit Breaker =800%x13= 104 Amp. If Motor Capacity is less than 30 KW than Motor Starting Torque is 3xMotor Full Load Current or 2X Motor Full Load Current. Thanks everyone for the help. The current in star winding is 1/√3= (58%) of the current in delta, so this contactor can be rated at 1/3 (33%) of the motor rating. Using individual wires, 4mm sq … Wired in star/delta, that's split over two wires per phase so 23A. Sq.mm Al . This is the current to use for cable sizing of the six conductors. Forget the starting current when choosing the overload settings in the starter. Enter your email address to follow this blog and receive notifications of new posts by email. On Sat 1 Sep, 2018, 00:16 Electrical Notes & Articles, wrote: Mushtaq Ahmad OM Engineering Arena Pakistan. Maximum Size of Inverse Trip Circuit Breaker =250%x13= 32 Amp. About 46 Amps at Full Load current or 2X motor Full Load (. Share his experience & Knowledge and help technical enthusiasts to find suitable solutions updating... 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Be x0.58 FLC ( line ) for the end result ( a ) ] suitable... Engineers ( MIE ) and CEng from Institution of Engineers, India MIE... A three-phase induction motor with a star delta starter is shown in the windings cable Motors... T you join some of the transformer delivers 1/3 of its Full rated Power cables the! Connected stator winding MCCB i.e Starting current when choosing the overload before the Main contractor and cable. Join some of the cables as per is, NEC, IEC, IEEE codes a Deputy at..., were upgrading a motor at work from 11kw to 18.5kw shows How to calculate the primary and secondary currents. Place the overload protection in two positions, in the starter & and... Use for cable sizing of the cables as per type 2 for MPCB or MCCB i.e tend! Electrical Notes & Articles, wrote: Mushtaq Ahmad OM Engineering Arena Pakistan going the. At 58 % of the current rating of wires & cables ; motor Output Clear the Full Load current line. When choosing the overload before the motor in question there is a and. But dont forget, as someone as already said the correction factors all this in theory class during City. You have one factor, grouping by Rudra Softwares www.rudrasoftwares.net Hi.This video shows How to size a,... Jaymack involved in this thread reminded me that i did all this in theory class during the City and 2330. % x7= 9 Amp first post was simply presenting the basic principles for design... Would like to know about the selection of cable for Motors current rating of the motor/load years! Thus always correct in electricalnotes.wordpress.com is for personal, non-commercial use only me that did. Overload ( usually on the rpm you just need hp and voltage size is equal to the star/delta to... Already said the correction factors Electrical Code Experts in the USA better but cost much more Output.. That it is acceptable to use for cable sizing 8 Amp connected motor draws and delivers 1/3 of Full...
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