Computerized instrumentation — Automatic measurement of contact resistance of metal to carbon relays used in railway signaling

The Contact Resistance of metal to carbon relays used in railway signaling systems is a vital quality parameter. The manual measurement process is tedious, error prone and involves lot of time, effort and manpower. Besides, it is susceptible to manipulation and may adversely affect the functional reliability of relays due to erroneous measurements. To enhance the trustworthiness of measurement of contact resistance & to make the process faster, an automated measurement system having specially designed application software and a testing jig attachment has been developed. When the relay is fixed on the testing jig, the software scans all the relay contacts and measures the CR. The results are displayed on the computer screen and stored in a database file.