1402 THE BELL SYSTEM TECHNICAL JOURNAL, NOVEMBER 1953 



AMPERE-TURNS 



20.4 



204 



10 



ID 

 2 

 H 2 



10- 



8 _p 



10 2 



POWER IN COIL IN WATTS 



1.0 



Fig. 7 — Time to close opposite contact after voltage is applied to coil, (A) 

 ±5 NX adjustment, voltage directly on coil. (B) Same as (A), except with resist- 

 ance equal to coil in series. (C) Operate +20.4 NX, release +9.9 NX voltage directly 

 on coil. (D) Same as (C), except with resistance equal to coil in series. 



mercury bridge does not ordinarily break until after contact is made on 

 the opposite side. 



SXhe natural frequency of the free armature, wet with mercury, is 

 about 220 cps. The relays have been used at frequencies up to about 350 

 cps where the drive conditions were individually selected with respect 

 to the phase of impact transients. Fairly well controlled operation with- 

 out such selection can be obtained up to about 100 cps. 



CONTACTS 



The relay has been designed with telephone, rather than power appli- 

 cations in mind. The contacts are smaller than those in the previous 

 neutral design, and this appears to be associated with less capabihty 

 for closure of very high current circuits. The capacity required across 

 the contact to prevent noticeable arcing appears to be about the same 

 as that required in the earlier type : 



C = 



— microfarads. 



but in most cases, larger values than this will be needed to hold peak 



