What is MDI (Maximum Demand Indicator) ....

HI all,

I am woking on Digital Energy meter 3 phase. During study i cam accros the requirnment of MDI display and MDI reset. Can anyone plz explain these two terms and logic to implement it.

What i understand is as follows..

MDI is a average reading of KW in a perticuler interval of time (normally 30 seconds). It is used to charge consumer an extrabill if consumer has consumed energy through excessive load then is limit.

My confusion is..

How to calculate it. When to reset MDI..

regards
Dani...

Your understanding of MD is correct.

There are 2 methods of calculating it:

1) Normal or Block method:
At the end of each fixws integ. period, average power for that period is calculated. If this value is greater than already existing valuethen this is stored as the MD

2) Sliding window method:
At the end of a sub integ. period the avg power is calculated for one integ. period. If this value is greater than the already existing value than this is stored as MD . the intg. period slides by a window of the sub. intg. period.

e.g.:

<pre>MD NO Method Intg. period Sub Intg. period
MD1 Sliding 30 min. 15 min.
MD2 Block 30 min. 30 min.</pre>
Assume a load pattern of following type:
<pre>T=09.00 T=09.15 T=09.30 T=09.45 T=10.00
20KVA 30KVA 30KVA 20KVA
15mins 15mins 15mins 15mins<pre>

For MD1 (Sliding window method)-
Demand - 09.00 to 09.30 block = (20*15+30*15)/30 = 25KVA
Demand - 09.15 to 09.45 block = (30*15+30*15)/30 = 30KVA
Demand - 09.30 to 10.00 block = (30*15+20*15)/30 = 25KVA
MD1 at the end of 10.00 = 30 KVA

For MD2 (Block method)-
Demand - 09.00 to 09.30 block = (20*15+30*15)/30 = 25KVA
Demand - 09.30 to 10.00 block = (30*15+20*15)/30 = 25KVA
MD1 at the end of 10.00 = 25 KVA

Normally MD is reset on the first of every month ie on a monthly basis.

For further clarifications & help you can mail me directly on :
meghalv @ rediffmail.com
meghalv @ hotmail.com

Dear Megha

Your write up on MDI was useful. I want to know if MDI exceeds the sanctioned load by say 20 percent in a particular month, I will like to know if it is reset on the next meter reading and if yes then i will like to know the reference or rule of electricity act. Please guide. regards
Dr J S Suri

- - - Updated - - -

Dear Megha

Your write up on MDI was useful. I want to know if MDI exceeds the sanctioned load by say 20 percent in a particular month, I will like to know if it is reset on the next meter reading and if yes then i will like to know the reference or rule of electricity act. Please guide. regards
Dr J S Suri

- - - Updated - - -

Dear Megha

Your write up on MDI was useful. I want to know if MDI exceeds the sanctioned load by say 20 percent in a particular month, I will like to know if it is reset on the next meter reading and if yes then i will like to know the reference or rule of electricity act. Please guide. regards
Dr J S Suri

- - - Updated - - -

Dear Megha

Your write up on MDI was useful. I want to know if MDI exceeds the sanctioned load by say 20 percent in a particular month, I will like to know if it is reset on the next meter reading and if yes then i will like to know the reference or rule of electricity act. Please guide. regards
Dr J S Suri