Electrical Notes

  Abstract of National Electrical Code for Size of Cable for Motors: NEC Code 430.22 (Size of Cable for Single Motor): Size of Cable for Branch circuit which has Single Motor connection is  125% of Motor Full Load Current Capacity. Example: what is the minimum rating in amperes for Cables supplying 1 No of 5 hp, 415-volt, 3-phase motor at 0.8 Power Factor. Full-load currents for 5 hp = 7Amp. Min Capacity of Cable= (7X125%) =8.75 Amp. NEC Code 430.6(A) (Size of Cable for Group of Motors or Elect.Load). Cables or Feeder which is supplying more than one motors other load(s), shall have an ampacity not less than 125 % of the full-load current rating of the highest rated motor plus the sum of the full-load current ratings of all the other motors in the group, as determined by 430.6(A). For Calculating minimum Ampere Capacity of Main feeder and Cable is  125% of Highest Full Load Current + Sum of Full Load Current of remaining Motors. Example: what is the minimum rating in ampe...

  ELECTRICAL MOTOR CONNECTION:   How to Change Rotation of Motor in Clockwise Direction No Present Motor Connection: Change Direction in Clockwise 1 R Phase Connected to U1 W2 R Phase Connected to U1 V2 Y Phase Connected to V1 U2 Y Phase Connected to V1 W2 B Phase Connected to W1 V2 B Phase Connected to W1 U2 2 R Phase Connected to W1 V2 R Phase Connected to W1 U2 Y Phase Connected to U1 W2 Y Phase Connected to U1 V2 B Phase Connected to V1 U2 B Phase Connected to V1 W2 3 R Phase Connected to V1 U2 R Phase Connected to V1 W2 Y Phase Connected to W1 V2 Y Phase Connected to W1 U2 B Phase Connected to U1 W2 B Phase Connected to U1 V2 Change Rotation in Anticlockwise Direction No Present Motor Connection: Change Direction in Anticlockwise 1 R Phase Connected to U1 V2 R Phase Connected to U1 W2 Y Phase Connected to W1 U2 Y Phase Connected to W1 V2 B Phase Connected to V1 W2 B Phase Connected to V1 U2 2 R Phase Connected to W1 U2 R Phase Connected to W1 V2 Y Phase Connected to V1 W2...

  Electrical Calculation and Electrical Notes on Electrical Engineering: All Notes ,Calculations & Abstracts are Based on Some Electrical References. All References are mention at end of each Notes. BUY All Electrical Notes & Calculation Sheets in PDF Format (US$) BUY All Electrical Notes & Calculation Sheets in PDF Format (Indian Rs) Electrical Notes:                                                . (1) Motor & Starter:                                                                                                     . Star-Delta Starter Direct On Line Starter Motor Name Plate Term...

  Introduction: For supplying a load in excess of the rating of an existing transformer, two or more transformers may be connected in parallel with the existing transformer. The transformers are connected in parallel when load on one of the transformers is more than its capacity. The reliability is increased with parallel operation than to have single larger unit. The cost associated with maintaining the spares is less when two transformers are connected in parallel. It is usually economical to install another transformer in parallel instead of replacing the existing transformer by a single larger unit. The cost of a spare unit in the case of two parallel transformers (of equal rating) is also lower than that of a single large transformer. In addition, it is preferable to have a parallel transformer for the reason of reliability. With this at least half the load can be supplied with one transformer out of service. Condition for Parallel Operation of Transformer: For parallel connec...