induction type overload relay

[shakerbess]

hi could anybody help need to find out the following please little stuck

question: show how an induction relay maybe used together with other components to protect against overloads and earth faults on the transition and distribution system

any help would be great thankyou

 

[malcolmsanford]

These are used on mains switch gear. They are normally activated by either time or current on a curve and are used as fault protection

I did cover this at one time but it's normally the domain of the HV guys. They are also sometimes known as protective relays.

I'm sure some of the HV guys on here will give you a better definition

 

[Knobhead]

They are an “inverse time relays” the current is first set and then the time delay. If you look in the regs you will see tables of current/time curves for MCCB’s and fuses. The relays are a more flexible way of doing it. O/L is only measured on the red and blue phases yellow is used for E/Fault
Some relays such as P & B Goulds have instantaneous elements.
PM me I will try to mail a drawing for you. It’s a bit complicated as the drawing I made includes all the HV/LV protection

 

[Engineer54]

They are an “inverse time relays” the current is first set and then the time delay. If you look in the regs you will see tables of current/time curves for MCCB’s and fuses. The relays are a more flexible way of doing it. O/L is only measured on the red and blue phases yellow is used for E/Fault
Some relays such as P & B Goulds have instantaneous elements.
PM me I will try to mail a drawing for you. It’s a bit complicated as the drawing I made includes all the HV/LV protection

Correct, many of these relays will have both overload and instantaneous for both the phases and earth elements. Most of the bigger LV ACBs /GCBs will incorporate an internal version of this type of protection.
While MV and HV generally have stand alone relay devices. Many such protection devices now come in a single multi protection unit, covering many types of protection relays...

 

[shakerbess]

thankyou for the information to all that replied huge amount of respect.

 

[shakerbess]

does anybody know where i could get information for transmission and distribution transformers need to compare core construction, winding arrangements and insulation. number of phases and mode of connection, (star/delta/zig-zag),cooling, tertiary windings, ancillary equipment, voltage range and voltage and power ratings im doing a project and could do with some direction please or information forwarding if possible thankyou

 

[mechelec]

you need this book, it covers a hell of a lot to do with distribution at 1036 pages it is not exactly a bedtime read but very useful reference book not cheap but i managed to get a PDF copy from amazon for £10

Transmission and
Distribution
Electrical
Engineering
Third edition
Dr C. R. Bayliss CEng FIET and​

B. J. Hardy ACGI CEng FIET

 

[shakerbess]

thankyou for information thats brillaint