Patent GB-358003-A (GB)
Title: Improvements in electrical time interval testing apparatus
IPC: H04M3/12
Filed: 1930-06-26
Abstract: 358,003. Light current relays. STAN. DARD TELEPHONES & CABLES, Ltd., CHAPMAN, S. and BROWN, A., Columbia House, Aldwych, London. June 26, 1930, No. 19472. [Class 38 (v).] An apparatus for testing the time of operation of an electromagnetic relay or contact-maker comprises a number of relays of varying release times a selection of which may be included for comparison against the tested relay by operation of corresponding associated switches, the times of operation of the selected relays being summated, for comparison with the time of operation of the tested relay. Control relays may also be provided for causing the illumination of lamps which indicate whether the tested relay operates in a greater qr smaller time than the marginal limits allowed or operates in a time falling within those limits. As shown in Fig. 1, the apparatus comprises standard time relays A .. H, the time elements of which are indicated on the corresponding control switches KA .. KH. The relay under test has its winding connected to points 1, 2 and its contacts to points 3, 4, these circuits being brought into operation by contacts of a relay T under the control of a starting key K. The initiation of the testing operation brings into operation a self-locking relay P which causes the initiation of the operation of the selected standard relays of the group A .. E which have been set to the minimum permissible time of operation of the tested relay. Each of these standard relays completes in turn the circuit of the succeeding one in the group AE. During the closure of the contacts of relays in the group AE the winding of the control relay P is short-circuited and at the end of their operation the short-circuit is removed and the relay P again operates. If, however, the tested relay operates before the minimum time has elapsed, a control relay Q operates before relay P so placing a gap in the circuit of relay P which cannot operate at the end of the minimum relapse time. At the end of the maximum permissible time of release determined by the setting of switches KF, GK, KH corresponding to relays F, G, H the relay R is operated. If the time of operation of the relay under test exceeds this maximum time the operation of the relay R takes place before the operation of the relay G under the control of the tested relay so that a gap is placed in the circuit of the winding of relay Q preventing its subsequent operation. Thus when relay K operates one of three lamp-circuits OK, F, SL is completed in the following manner, viz. the circuit of lamp OK if the relay Q operates after relay P and before relay R, the circuit of lamp F if the relay Q operates in advance of the reversal of the short-circuit of relay P and the circuit of lamp 34 if the operation of the relay R takes place before the operation of the tested relay contacts can close the circuit of relay Q. Relay T is made slow to release in order that the lamp which has been lit shall remain so for an appreciable period. The relay T is under the control of a slow-acting relay 3 so that while the switch K is closed a succession of testing cycles continues at the end of each of which the lamp corresponding to the time characteristics of the relay under test is illuminated. In Fig. 2 is shown the assemblage of apparatus. An upper panel J on a U-shaped chassis U mounted on a base V carrying the switches 0, indicating lamps N and terminals M. The control, relays and resistances are mounted within metal cases L.