KYORITSU 6300 Instruction Manual - Manual (Page 13)

1. 5
MODEL6300
Section 1 Instrument overview MODEL6300
1-4 Outline of maximum 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.
Ɣ 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 15
th
January) is 600kW .
Then the new applicable rate from 1
st
Febraury onwards will be the
600kW/year rate (ie. $5) for the next 365 days. If a year later, on February
1
st
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 15
th
March, the applicable rates change again to the
600kW/year rate (i.e.$5) for the subsequent 365 days.
Ɣ 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.
Ɣ 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.