Web admin (Fig1-XLPE cable) Cable Sizing There are a various cables available in the market in various sizes. But, to decide which size will be appropriate for our application and requirement , we may require an Electrical Cable Size Calculator,selecting cable size as per our unique requirement is also called cable sizing. This helps us understand the best … Read more
Why do we need Trip circuit Supervision relay? A trip circuit supervision relay as the name indicates , its function is of supervisory nature. A trip circuit supervision relay monitors healthiness of tripping circuit and indicate whether the circuit is healthy or unhealthy so that preventive action can be taken accordingly. All faults are detected … Read more
Transformer is a static device which works on principle of electromagnetic induction. Transformer faults can be broadly classified as external and internal faults. External transformer faults External transformer faults in the transformer are usually transient (not occurring for long time) in nature and they are easily detected and rectified accordingly. Faults occurring outside the transformer, … Read more
Air insulated substations(AIS) and Gas Insulated substations(GIS) Broadly there are two types of substations : Air insulated substations(AIS) and Gas Insulated substations(GIS). In AIS all electrical equipment like CT, circuit breaker, Isolators etc are installed in the open air in the switchyard, however in GIS these electrical equipment are installed within closed chambers which is … Read more
Restricted earth fault Protection as the name suggests protects the restricted (fixed area) part of transformer from earth fault. This restricted part here implies the inside part of transformer only. That means that REF protection covers only the internal ground faults and for external ground faults separate earth fault relays are used. Unlike conventional earth … Read more
Transformers work on principle of electromagnetic induction , their primary purpose is to change (Increase or decrease) voltage level. Types of transformers depend on their construction, application, and voltage levels. Main types of transformers: 1.Types of transformers on the basis of Input/Output Voltage level : 2.Types of transformers on the basis of Power rating: 3.Transformer … Read more
Digital Earth Tester Digital Earth tester is used to measure earth resistance. Earth resistance refers to the impedance offered by the ground or soil to the flow of electric current. Its value is very important in electrical engineering, as it is directly related with safety of electrical systems, grounding systems for buildings, power distribution networks, … Read more
Star point in a Current transformer decides the direction in a directional relay as well as energy meter import/export direction. Star Point in a Current transformer (S1,S2,S3 etc) is chosen as per following conditions and requirements: a) Physical placement of the C.Tb) Orientation of the element to be protected w.r.t C.T andc) Desired C.T ratio. … Read more
While constructing/re-routing any transmission line ,it is mandatory that minimum electrical clearance standards are adhered to for the safety of man and materials and for uninterrupted power flow. Below mentioned clearances are as per CEA guidelines. 1.Minimum Electrical Clearance from the ground Minimum ground clearance of the conductor from the ground needs to be maintained … Read more
DC supply system in a substation consists of battery bank, battery charger, DC distribution board and control gear.Battery bank are either lead acid or dry cells type and battery charger used can float charge the battery while they are on load and it also has boost charging function. Generally we use two DC battery banks … Read more