Reading 2

Task 8

Read the text and think of Russian equivalents to the words in bold.

Measurable parameters

Supply, demand and capacity

Calculating the capacityof an electricity grid - the amount of energy it needs to supplyto users - might seem simple. Just add up the power supplied over a given periodof time to give the total amount consumedby users. Then, divide the cumulativeamount of power used during the whole period by the number of hours in the period. The result is an averagelevel of consumptionper hour. But there's one problem with this method - and it's a major one.

The rateof power consumption - the amount that's being consumed at a particular moment - is not constant.In other words, consumption does not stay at the same level all the time. So electricity supplyrequirements cannot simply be averaged outover time. People use more power at certain times of day, and less at other times, which means that demandfor power fluctuatessignificantly. Generally, it rises to a maximum in the evening (peakdemand is at evening mealtimes), and falls to its lowest levels during the night. These fluctuationsare so big that at peak timesconsumption can be twice as high as it is during off-peak times.Clearly, the grid needs to have sufficient capacity to meet demandwhen consumption peaks.But since each peak is brief, the grid will only run to capacity- at or close to its maximum capability - for a few moments each day. This means, most of the time, it has significant spare capacity.