Secondary Measuring Instrument

the element of a measuring information system that indicates or records the values of the quantities being measured. There are various modifications of secondary measuring instruments: single-channel types, which indicate or record; multichannel types, which simultaneously indicate and record the values of several quantities; multipoint types, which automatically alternately indicate and record the values of several homogenous quantities being measured; types that total the values of several quantities being measured; integrating types, which give an integrated (total) value for the quantity being measured after a certain time interval; signaling types with a light or sound signal device that is triggered when the value of the quantity being measured goes outside set limits; and regulating types, which generate a control signal.

Secondary measuring instruments with built-in measuring transducers are becoming increasingly common. This makes it easier to combine the measuring system, for example, with automatic control devices or computers.

The requirements for the technical specifications and de-signs of secondary measuring instruments are similar to requirements for indicating and recording measuring instruments. For secondary measuring instruments the primary errors of reading, recording, and integration are given separately and, where there is a built-in transducer, the primary error of conversion and other precision characteristics are indicated.