Capacitors in Series and Parallel

Capacitors in Series and Parallel Capacitor in Series Let us connect n number of capacitors in series. V volt is applied across this series combination of capacitors. Let us consider capacitance of capacitors are C1,C2, C3…….Cn respectively, and equivalent capacitance of series combination of the capacitors is C. The voltage drops across capacitors are considered…

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soft starter

Difference between DOL, Star Delta, VFD and Soft starter

DOL-Direct on line Starter: here the starting current will be 6 times of full load current. A bimetallic thermal overload relay provides protection against the over load. There will be no reduction of starting torque during starting. Star Delta Starter: In order to limit the starting current of motors this method is followed. Initially motor…

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Battery charging calculation

How to Calculate the charging Time and Charging current for battery Charging? Easy Battery Charging Time and battery Charging Current Formula for Batteries. ( with Example of 100Ah Battery). Battery Charging Current and Battery Charging Time formula Here is the formula of Charging Time of a Lead acid battery. Charging Time of battery = Battery…

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Circuit Breaker Tripping Schemes

Circuit Breaker Tripping Schemes Basically two types of tripping schemes which are given below:- Relay with make type contact. Relay with break type contact.   1) Relay with make type contact: In this scheme, the relays are connected in the stare, and contacts of each relay are connected in parallel and this parallel unit of…

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armature winding

Magnetic Saturation

If we increase the mmf of a magnet, the flux density inside the core to of the is also increased. Now we can ask a question, whether there is any limitation of increasing flux density in the core of magnet with increasing applied mmf. The answer is yes. There is a limit beyond which there…

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generator troubleshooting

Troubleshooting guide for generator

Brief introduction The following problems listed below are provided the following: Known problems Possible causes of the known problems Repair to correct the known problems Fault diagnosis   1). When the starting switch is in the (ON) position, the engine crankshaft does not rotate. Possible causes: 1. Low battery output voltage Check the battery status…

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neutral ground resistor

Neutral-Grounding-Resistor System

Neutral-Grounding-Resistor System Neutral-Grounding Resistors (NGRs) are used to ground power systems by inserting a resistor between the system neutral and ground. This lowers the prospective ground-fault current to a predetermined value. A properly designed resistance-grounded system provides benefits over both ungrounded and solidly grounded systems. Because the system is grounded, transient over voltages do not…

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What is Motor soft starter

Motor soft starter A motor soft starter is a device used with AC electrical motors to temporarily reduce the load and torque in the power train and electric current surge of the motor during start-up. This reduces the mechanical stress on the motor and shaft, as well as the electrodynamic stresses on the attached power…

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restricted earth fault

Restricted Earth Fault Protection of Transformer | REF Protection

REF Protection: An external fault in the star side will result in current flowing in the line current transformer of the affected phase and at the same time a balancing current flows in the neutral current transformer, hence the resultant current in the relay is therefore zero. So this REF relay will not be actuated…

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basic electrical

Basic Electrical interview Questions & Answers

1.What  is  electricity ? Ans : Electricity is a general term used for all phenomena caused by electric charge whether static or in motion. 2.What are the types of electricity ? Ans : There are two types,(1) static Electricity and (2) Current Electricity. 3.What is static electricity ? Ans : Static electricity means electricity at…

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