SEG Electronics GmbH Manual MRR1
18 DOK-TD-MRR1, Rev. B
6.4.2 Example of a test circuit
Figure 6.1 shows a simple example of a test circuit with variable current source for testing the re-
lay.
Figure 6.1: Test circuit
6.4.3 Checking the insulation measuring circuit
For checking the insulation measuring circuit a resistor with a defined value is simply connected to
terminals A2 - A3/A4 (A3 and A4 are to be bridged). By pressing push button <SELECT/RESET>,
measuring value R is displayed. This value must be identical with the de-fined value.
6.4.4 Checking the excitation current circuit
For checking the measuring values a current must be injected (terminals B1 - B2) which is below
the set pickup current of the MRR1. After renewed pressing the <SELECT/RESET> push button,
measuring value le is displayed and can be checked by using an ammeter.
Example : For this test circuit the dc current is generated from a single-pulse rectification. If a cur-
rent of IAV = 5A is fed to the MRR1, this value has to be indicated at the display. By repeatedly
pressing the <SELECT/RESET> push button, measuring value Ir is displayed.
Due to the conversion factor for single-pulse rectification of 0.318, the peak value at an average of
IAV = 5A comes to 15.73A. The ripple is calculated by using the following formula :
The measuring value Ir resulting from this is 314 %.
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