In practice the requirement often arises to convert the measurement signals of a sensor into a standard signal in the simplest possible manner in the immediate proximity of the sensor. This permits trouble-free, low-loss transmission of measured values over longer distances to an instrument board or plant controls.
Ideally suited for this purpose is the in-line measuring amplifier, which is inserted in between in the connection cable by means of plug contacts. Owing to its compact, robust design and low weight, it finds use in almost any application. Even movable locations subject to forces of acceleration, for example manipulators, present no problems. It is intended mainly for use of control cabinets in just about any location and is matched to a specific sensor. The aluminium housing is extremely sturdy and affords the greatest possible protection even in harsh environments.
The in-line amplifier module itself is operated at voltages between 15 V and 30 V, from which it generates a stable excitation voltage to supply the sensor with power. The measurement signals of the sensor, normally ranging between 0 ... 5 mV and 0 ... 10 mV for bridge-connected strain gauges, are amplified to analog 0 ... 10 V.
The sensor characteristics are first roughly preset by means of DIP switches, through an opening in the housing. The fine-tuning of the instrument zero and amplification settings is performed by means of a multiple trimmer, accessible by screwdriver through holes drilled in the side of the housing. The amplifier connections are realized with sub-D plug and socket; short circuit-proof sensor power excitation and polarity reversal protection for the amplifier power excitation afford additional safety for installation. If the amplifier has to be mounted to its environment, this is done by clamping the housing or affixing it with an adhesive. The amplifier’s cut-off frequency is > 1 kHz, its weight is < 65 g.