View technical details collected from various sources

Frequent interaction with statutes, industrial standards, codes of practice and even some theoretical aspects is required in the professional career. This page contains some of the links which we have collected from various sources.

Cable Sizing Calculator:  Calculates the appropriate cable size required for servicing induction motors with DOL starting scheme. The required inputs are a) motor capacity in kW 2) full load current (optional) and 3) distance of motor from the control centre. Read more...

Motor starting and running currents and switch gear rating:  An overview of how to calculate the starting and running currents and to arrive at the rating of required switch gear. This article is based on NEMA standards and is oriented more towards the US industry. Read more...

Motor Duty Cycles:  Most of the motors we encounter in normal practice are continuously rated motors (S1), but there are some applications which employ motors of other duty types like S2, S4 etc. An overview of various duty cycles based on IEC 60034-1. Read more...

Insulation Class of Windings:  Windings of motors, transformers etc are designated as having insulation classes B, or F etc. A round-up of the available insulation classes and the maximum temperatures upto which each can be loaded. Read more...

Motor Cooling Systems:  Cooling systems of motors and other rotating machinery are often indicated using IC numbers. An overview of the numbering scheme is given here based on IEC 60034-6. Read more..

Motor Starting Schemes:  A discussion on the starting schemes of motors. Various alternatives like DOL, Start-delta and their relative advantages are discussed. This section also addresses the question most often articulated by beginners when they see large motors started in DOL in industry too often which is contrary what they learned in academy.  Read more..

Effects of frequency and voltage variations on performance:  Various parameters of motors like torque, speed, efficiency, pf, current etc are dependent on the applied voltage and frequency. Click to find the variations and more details. Read more..

Approximate Rated motor currents:  A table showing approximate motor rated currents for various capacities and voltages. Can be used as a ready table for finding out the full load current.  Read more..

Motors for hazardous locations:  In areas where explosive gas/air mixtures are present, ordinary TEFC motors are not enough to ensure safety of personnel and surroundings. Special purpose motors are to be used here.  Read more..

A discussion on Overload Relays:  Thermal over current relays are the most common, inexpensive and effective method of protection. Learn more about them.  Read more..

Selection Chart for Type 2 Coordination DOL Starters(for L&T Switch gear):  A comprehensive chart for L&T switch gear including contactors, over load relays, fuses and isolators for type 2 coordination of motors having rating from 0.09 kW to 315 kW.  Read more..

Selection Chart for Type 2 Coordination Star-Delta Starters(for L&T Switch gear):  Similar to the above, but for STAR-DELTA feeders for motors having rating from 0.75 kW to 375 kW.  Read more..

Selection Chart for Type 2 Coordination Fuseless DOL Starters using MPCB/MCCBs (for L&T Switch gear):  Similar to the above, but for fuseless DOL feeders having MPCB/MCCBs.  Read more..