Test Procedures for the Communications Technology
13.3.1 Measuring of Contact Resistance
The contact resistance in the new stage is for most contact containing electromechanical components a characteristic defining their quality. It is defined in most standards and acceptance specifications of users. It is important however that a clear definition of the test conditions is given with the specification.
The standard IEC DIN EN 61810-2 defines the application areas of relays according to their load application categories (CC) (Fig. 15.5). The categories CC1 and CC2 are separated by the arc-limiting graph (DC breaking capacity). Switching operations below the graph do not generate electrical arcs, those above the graph are accompanied by electrical arcing.
- CC1 is characteristic for switching operations in control circuits at low voltages, for ex. SPS input signals
- CC2 is typical for release circuits in low voltage controls which for example actuate contactors (220 - 240 VAC)
- CC0 describes as a special application the voltage – current range for dry circuits
Fig. 13.5: Schematic describing the contact load categories in in the current-voltage ranges according to IEC DIN EN 61810-2. Arc-limiting graph for an arc duration < 1 ms
The measuring conditions for contact resistance measurement are defined per IEC DIN EN 61810-7 for the contact load categories as follows:
- Contact load category CC0: < 30 mV; < 10 mA
- Contact load category CC1: < 10 V; < 100 mA
- Contact load category CC2: < 30 V; < 1 A
