KYORITSU 6310 Instruction Manual - Manual (Page 18)

1.5 Outline of max demand measurement concept KEW6310
1.7
KEW6310
1.5 Outline of max demand measurement concept
In some countries, large consumers of electricity will usually have a maximum demand contract with the power
company. Such contract varies from country to country. The following is an explanation of a typical Japanese
maximum demand contract.
● Maximum Demand contract
In such a contract the electricity tariff rates (i.e. for kWhr units) are based upon the consumer’s maximum
power demand. The maximum demand is the maximum of average powers recorded over a 30min intervals.
This is measured by the maximum demand meter belonging to the power company. Let’s assume that a power
company has the following applicable rates.
$2 per KWhr unit for a recorded max demand 300KW during a year
$4 per KWhr unit for a recorded max demand 500KW during a year
$5 per KWhr unit for a recorded max demand 600KW during a year
Assuming that the consumer is on the 500kW/year rate (ie. $4), and the recorded max demand during a
particular day(say 15th January) is 600kW . Then the new applicable rate from 1st February onwards will be the
600kW/year rate (ie. $5) for the next 365 days. If a year later, on February 1st the recorded maximum demand
is 300kW, then the new applicable rates will be changed to 300kW/year rate (i.e. $2) for the subsequent 365
days. However if during this period, the max demand goes up again, and say 600kW is recorded on 15th March,
the applicable rates change again to the 600kW/year rate (i.e.$5) for the subsequent 365 days.
● Benefits of maximum demand control
It is thus important for consumers with such contracts to monitor closely fluctuations in their power demand to
ensure that their max demand limits are not exceeded and thus incur higher tariffs. Maximum Demand control is
more effective in countries with higher electricity tariffs.
● Status of maximum demand contract
In the past, in Japan, only consumers whose electricity supply was rated at 600kW or more used to enter into a
demand contract. However, nowadays power companies install maximum demand meters at all consumers
whose supply is rated 70kW or more.
● Maximum Demand measurement limitations
N.B. The readings from power company maximum demand meter and from the 6300 will not match completely
due to an obvious time-lag difference in the start of the integration period (eg.30mins) over which the max
demand is taken.