Description
The voltage and current monitoring relays of the 8981 series were developed especially for points heater controllers with an operating voltage of AC 463 V, 16 2/3 Hz, as is used in railway operations. These monitoring relays can also have their voltage range set for any other application that requires the monitoring of the presence of the voltage or the flowing of a specified current in the range from 5 to 20 A. The devices can also be used in the range 230 V 50 Hz, but without application of the IPH test report.
The current monitoring relay is still made today unchanged from the form produced under the old company name (Pepperl + Fuchs) and the old type number (854299). Under this type number and company name, the device was tested and approved by the institute »Prüffeld für elektrische Hochleistungstechnik« GmbH (Test Centre for High-Power Electrical Systems) in Berlin.
Function
In the case of the type 898110 voltage monitoring unit, if the measured voltage that is at the same time the supply voltage is above the fixed trigger value of approx. AC 120 V that had been set at the factory (other values are available on request), the built-in output relays draws in, the output contact is switched over and the green LED lights up.
If the measured voltage drops by 33% below the trigger value, the output relay drops out again, the output contact switches back and the LED goes out.
With the type 898120 current monitoring unit the current to be monitored between terminals L2 and L2´ is passed through a resistance of 6 mΩ. The voltage drop produced as a result of passing through the resistance is passed on for an evaluation whose trigger point can be set. In this way it is possible to monitor currents in the range from 5 to 20 A. If the current exceeds the preset value, the output relay switches and a red LED indicates that the switching threshold has been exceeded.
If the current being monitored drops by approx. 1.25 A below the preset threshold, the output relay drops out again, the output contact switches back and the LED goes out.
Special configurations of the voltage and current monitoring relay are available on request. See the complete brochure folder for additional units for the voltage range AC 463 V 16 2/3 Hz, for example, isolating switching amplifiers for temperature sensors or the like.
