AC voltage measuring device BOQ series

frequencyACmechanical

The maximum demand indicator consists of a bimetallic spiral which is expanded by the heat caused by the current circulating in it, driving the pointer. A second spiral, mounted in the opposition, compensates the effect of the ambient temperature. The ammeter uses a moving-iron movement with silicone oil damping and pivot suspension with spring loaded jewel bearings for vibration and shock resistance. They combine a maximum demand meter and a moving iron ammeter in one instrument. Due to its long response time, short interval current peaks are not registered and the instrument indicates by a black pointer the mean of the r.m.s. current in a specified period of time (15 minutes). The maximum indication is registered by the position of the red pointer, dragged by the black one. By means of a sealable knob it is possible to resetthe red pointer to the position of the black one in order to make a new reading. Moreover, they use the moving iron ammeter for measuring the rms value of the current at any racy. Overload capacity according to DIN 43780 Continuously 1,2 times nominal value Short duration 10 times nominal value Saturing current transformers shall be used to protect the instruments against overloads exceeding this rating. Scales The full -scale value is 1.2 times I n, (In is the rated primary current of the current transformer). 90º scale, quadratic. Coarse-fine division.