Maximum Demand meter is used for monitoring thermal loading in Power Distribution systems, networks, machine etc. It indicates maximum loading current over a period. Short-period current perks are not registered but long overloads are registered.
In the Maximum Demand meter the measuring current flows through the bimetal spiral which is temperature sensitive. The free end of the spiral is connected to a black measuring pointer. The moving system is activated by heat generated by the current flowing through the spiral. The instrument is provided with an additional red slave pointer with a higher friction, which makes it to remain at its maximum position, which determines the maximum average loading current. To prevent false indication due to fluctuations in a ambient temperature, an additional bimetallic spiral is wound in opposite direction, which is mounted on the same spindle to compensate variation in temperature from 10 to +55 degrees centigrade.Frequently there is a need to measure instantaneous current simultaneously & hence moving iron movement having the same range is incorporated in the same meter.Features
