Test relay 55
The test relay 55 is a plug-in relay from EMD technology. It consists of two independent relay systems.
task
When establishing a connection in EMD technology, the voters checked a large number of contact lamellas at high speed and had to stop very quickly on the contact lamella when they reached a free connection path. The free dialing speed of an EMD voter was very high during the search with 140 steps per second, the voter needed only about 7 ms to get from one contact to the next. A normal flat relay from EMD technology could not have stopped the voter in time. A fast switching relay was required that could safely shut down the voter. This is why the specialized test relay 55 was used in EMD technology, which had a correspondingly short response time due to its design. The relay must respond so quickly that when the selector is stopped, the test arms do not leave the contact lamellae on the contact multiple during the swinging out (pendulum movement).
construction
In the test relay 55, two relays were combined under a protective cap, namely the actual test relay (abbreviation P ) and an auxiliary test relay (abbreviation Ph ). The P relay was a small round relay and, with its response time of less than 1 ms, immediately shut down the EMD selector by connecting the motor windings (M1 and M2) of the EMD selector in parallel. The picture at the bottom right shows the contacts of the small, fast test relay. Simultaneously with the shutdown of the selector, the larger Ph relay was switched on by a contact of the fast P relay, which had the task of switching additional circuits. The Ph relay could operate a larger number of contacts. The windings of the auxiliary test relay were dimensioned so that a double connection was not possible. The armature of the auxiliary test relay carried a small white flag which, when the armature dropped, touched a white surface on the opposite side. When the armature was tightened, an air gap was formed which, like an indicator, indicated the status of the relay. This display provided a simple visual occupancy display for the relay set. The compact double relay (P and Ph) had a 24-pin connector and was quickly exchangeable.
Each individual contact spring of the fast test relay could be adjusted using two plastic screws (black in the picture). These plastic screws were provided with a locking varnish after the adjustment. This prevented the relay from adjusting itself due to vibrations.
literature
- August Kruckow: The self-connection and voter facilities in the telephone company. Friedrich Vieweg & Sohn Verlag, Wiesbaden 1911.
- Heinz Körber: Basics for telecommunications technicians. 2nd edition, specialist book publisher Dr. Pfanneberg & Co., Giessen 1965.
Web links
- Test relay 55 (accessed on July 10, 2017)
- Telephony (accessed July 10, 2017)
Individual evidence
- ↑ Test relay 55 (46). Retrieved May 7, 2019 .
- ^ A b Heinz Körber: Basics for telecommunications technicians. 2nd edition, specialist book publisher Dr. Pfanneberg, p. 28.
- ↑ Test relay 55 (108). Retrieved May 7, 2019 .