third paragraph the I ast sentence definitely does not apply to the new type CO relay.The new E ele ment is adaptable, if desired, to a curve less inverse than the General Electric Company inverse curve (matching the Westinghouse COI curve) and still have the curve continue steadily downward beyond 20 times tap value current.Mr. Cordray must be speaking of his own equipment when he states that the extremely inverse curve can be obtained only by measures so strenuous that he has to use a different type of electromagnet. The extremely inverse CO relay, the type CO-10, was obtained through changing the design proportions of the very inverse CO relay, and this did not necessitate the use of a radically different electromagnet.Separate style numbers have been assigned to relays having different calibration characteristics, the inverse and the very inverse, solely as a matter of user convenience. We do not consider this to be a manufacturing advantage, because it is not. Neither is it such a major task to change from one calibration to the other in the field as Mr. Cordray seems to indicate. With a test circuit and timer, it appears to the author to be only a trifle more time consuming to change the damping magnet for one point on the curve and the plugs for another point on the curve than it is to make a routine current-time check which many users do on periodic inspection. Whether or not the users will consider this an advantage is something that time will tell. As manufacturers, we believe that it will be, particularly since it can be used to simplify a stocking problem.We believe that the matter of controlling the quality of the electromagnet steel, such that adjustment to compensate for variation in quality are unnecessary, is idealistic. It seems to the author to be fundamental that if vernier controls can be incorporated in the relay design, closer tolerances can be held than will ever be realized by the allowable tolerance limits which can be placed on magnetic steel.When reset times are compared, it is important to select the right common denominator. For example, the correct reset time of 82 seconds at the number 11 time dial on the inverse CO relay should not be compared with the reported 6 seconds for the inverse IAC. The reset of the inverse IAC should be compared with the reset of the type COI relay. The statement "Long reset time is characteristic of low torque levels and heavy drag magnets" would be better omitted, because it is an incomplete coverage of the subject and is therefore misleading. Reset time was adequately covered in another paper.1 Heavy drag magnets are necessary to get large time values at low currents. Whether the torque level is low, high, or intermediate depends upon the efficiency of the electromagnet, the shape of the curve to higher current values, and other factors. Large operating time values at low currents are necessarily associated with long reset times when a clutch is not used. This is true regardless of the torque level. Mr. Cordray's own curves illustrate the fact that th...
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