Demand is a measure of average power consumption over a fixed time interval. Maximum (or peak) demand is the highest demand recorded over the billing period. The billing period is mostly end of the month.

Non-domestic electrical power users often have to pay a maximum demand charge in addition to the charge for the consumed energy. This additional charge is based on the highest amount of power used over a period (e.g. 15 minutes) during the billing period.

CLOU meters can operate with a fixed window or with a sliding window. Please note that not all meters have this function.

**What is the difference?**

The fixed window is defined in certain steps (e.g. 15 minutes), starting at the full hour. It can be programmed for the following fixed intervals:

- 5 minutes
- 15 minutes
- 30 minutes
- 60 minutes
- At the end of each fixed window period, the average power for that period is calculated. If this value is higher than the already existing value, it is stored as the MD (maximum demand).

The sliding window is the CLOU default setting. For sub integration period the default is 1 minute.

At the end of a sub integration period the average power is calculated for one integration period. If this value is higher than the already existing value then this is stored as MD. The integration period slides by a window of the sub integration period.

The maximum demand register MD will be reset at the set transferring time of each month (e.g. 1^{st}of each month). The demand values measured with 6 digits, including 4 integers and 2 decimals.

#### What is the impact on using different intervals and sub-intervals?

In the example below we are generating a 24 hour load-profile. It’s based on values between 30% peak and peak. (1440 samples)

Then we run a evaluation of the MD (maximum demand) for various meter settings. All fixed windows starting at midnight (00:00).

**What do we learn?**

- The shorter the integration period, the higher the MD value
- The shorter the sub-interval in the integration period, the higher the MD value (except of some strange profile constellations, you might find them)

**What are the right settings?**

It depends on the purpose for the demand measurement.

If you want to give a penalty to customers exceeding a defined limit, you need to follow the utility rules (e.g. 30 minutes fixed window).

If you are operating with an AMI system, you want to do a load-prediction (forecast) for a period of time. Here it is very common to use a 15 minutes integration time with 1 minute sub-intervals.

new random load profile | ||
---|---|---|

MD Limit | kVA | |

Peak load | kVA |

Integration period 5 minutes | ||

Integration period 15 minutes | ||

Integration period 30 minutes | ||

Integration period 60 minutes | ||

So far I thought that MD is the peak or max instantaneous KVA which we draw from the system for the specified time period.

But is it the average KVA value over a time period??

It’s always the average power for the selected interval time (integration period). The shorter the time interval, the higher is the MD for the same load profile.

Sir i have doubt that the meter is taking

the value of KVA at 5 min or value obtained at 5min is integration of 1s value.

The meter itself has a fixed integration time for energy recording. It’s typically 500 ms. This energy is incremented for the selected time period (in your case 5 minutes) and divided by the time period. Then we have the power (kVA) for this period.

What is the MDB for domestic? and is it different to Business?

The maximum demand measurement is mainly implemented for big consumers. It’s helpful for utilities to avoid big peaks by giving a penalty for exceeding given limits. Now you can find many domestic meters in the market with this feature but it’s rarely used for home.

Nevertheless, together with an AMI system the retrieved data are helpful for planning of power generation.

I need more information on maximum demand meter calculations

If our post is not clear, please ask a specific question.