Indepth Electrical engineering

There are two types of Tap changers in Transformers depending upon the rating of transformer. Off-load Tap changer On-Load Tap changer If a tap-changer is designed to operate with the transformer out of circuit the it is called off-load tap changer. In that Transformer line should be disconnected completely before changing the tap. If a Tap changer is designed to operate with the transformer in circuit then it is called as On-Load tap changer i.e. tap can be changed even when transformer will remains in line. Read about about why and where tap changer required in Transformer:- Read here Let’s discuss here about off –load or No load Tap changer:- No Load Tap Changer:- This type of Tap changer is used for seasonal voltage variations as in Summers load on HT increases leads to drop in HT voltage so O/P can be increased by using Transformer Tap changer and in Winters when load get reduced HT voltage restores to normal levels then tap changer position can be do...

Universal Motors – Working, Characteristics, and Applications What is a Universal Motor? A universal motor is a type of series-wound commutated motor that can operate on both AC and DC supply . It is essentially a DC series motor modified for AC operation . These motors are compact, inexpensive, and capable of running at very high speeds, making them ideal for household appliances and portable power tools. Applications of Universal Motors Universal motors are widely used in small and medium appliances where variable speed and high starting torque are essential: Power tools (drills, grinders, saws) Food processors & mixers Vacuum cleaners Sewing machines Washing machines (agitation + spin cycles) Hair dryers & small domestic appliances Construction & Operating Principle Series-wound design : Armature and field winding connected in series through a commutator. On AC supply : Current reverses in both arm...

Why Tap Changer required in Transformer?? Every equipment  is designed to operate at a particular voltage level. So it becomes extremely important to keep that voltage within limits. To keep terminal voltage within limits transformers are provided with tap changers. Tap changer can be provided either on primary or secondary depending upon requirement. Principle behind the tap changer is same. For regulating secondary output voltage no. of turns in primary or secondary winding are changed. e.g. let V(p),N(p) and V(s), N(s) are primary and secondary quantities. If N(p) decreased emf per turn on primary winding i.e. V(p)/ N(p) increases therefore it will leads to increase in O/P voltage as Secondary O/P voltage is {V(p)/ N(p)} XN(s). Similarly if N(s) is increased and N (p) kept constant then by same formulae we find that same effect on primary and secondary voltages. So we can say that decreasing primary turns and increasing secondary turns have same effect on vol...

Soft-Starter is a Solid State device used for starting of motor . Soft- Starters temporarily reduce the load and torque on motor during starting of motor. This will leads to reduced mechanical stress on the motor shaft as well as electrical stress on Power cables and whole electrical systems. In Typical Star-Delta Starter Starting current is about 3-6 times rated current of motor but using Soft-Starters this staring current can be reduced to 2-4 times motor rated current. This is ultimately reduces stress on electrical system which will leads to smooth running of electrical systems. In that Soft-Starter reduced voltage is applied during starting and that reduced voltage will reduce Starting torque. if 50% voltage is applied to a motor, it will produce 25% of it's available torque at that point. Starting time also feed into soft-Starter parameters , when motor get accelerated Soft-Starter get bypassed by soft-starter through bypass contactor provided inside Soft-Starter. Bypass...

Residual Current Detector:- Residual current detector works on the principle that amount of current flowing through phase should return through neutral as both phase and neutral are connected to RCD’s . RCD detects any mismatch between two currents that is through phase and neutral. RCD tripping value is usually in milliamp and mostly available in 30mA and 100 mA tripping range. If a house has an earth system connected to an earth rod and not the main incoming cable, then it must have all circuits protected by an RCD A current flow of 30 mA  is sufficiently small that it makes it very difficult to receive a dangerous shock. Even 100 mA is a relatively small figure when compared to the current that may flow in an earth fault without such protection. The residual current device – principle of operation The residual current devices monitor the current flowing in a circuit by means of a torroid, which is a small current transformer specially designed to detec...

Induction Motor Nameplate Details as per NEMA Standards Every induction motor comes with a nameplate , which acts as the motor’s identity card. It provides crucial electrical and mechanical information that helps engineers, technicians, and operators select, install, and maintain the motor properly. The National Electrical Manufacturers Association (NEMA) has defined minimum requirements for motor nameplate data to ensure uniformity across manufacturers. Below are the standard abbreviations and parameters typically found on induction motor nameplates, along with their importance: 1. Manufacturer’s Type & Frame Designation What it means : Identifies the manufacturer, motor type, and frame size. Why it matters : The frame sets mounting dimensions such as foot-hole pattern, shaft diameter, and shaft height. This ensures interchangeability between motors of the same rating from different manufacturers. Note : Some dimensions like overall height, conduit-box extensio...

Disadvantages of Variable Frequency Drives (VFDs) While Variable Frequency Drives (VFDs) offer many benefits such as energy savings, soft starting, and precise speed control, they also come with certain limitations that must be considered before selecting them for industrial applications. Below are the key disadvantages of VFDs: 1. High Initial Cost VFDs are more expensive compared to traditional motor starters such as DOL (Direct-On-Line) and Star-Delta . The initial investment often discourages smaller plants from adopting VFDs, despite the long-term energy savings. Payback period generally ranges between 1 to 2.5 years , depending on load type, operating hours, and energy tariffs. 2. Maintenance & Troubleshooting Require Specialized Skills Traditional starters are simple and inexpensive to maintain; failures can usually be identified by basic inspection . VFDs, being solid-state electronic devices , require: Special test equipment Skilled and t...