| 摘要 |
1,189,650. Protective systems. JAMES ARCHDALE & CO. Ltd. 6 June, 1967 [29 June, 1966], No. 29184/66. Heading H2K. An adjustable current sensitive relay arrangement for a D.C. machine comprises an adjustable resistor 1 for connection in series with the machine 2 to produce a D.C. signal voltage, a trigger circuit 7, 21 to an input terminal of which the D.C. signal voltage is applied, an adjustable biasing circuit 14 . . . 16 for applying to the input terminal a variable D.C. bias voltage in opposition to the D.C. signal voltage and an electromagnetic relay 27 operable by the trigger circuit. The arrangement is inoperative when the machine is being started, but is rendered operative when the contacts 13 of a timer T are opened. When the signal voltage overcomes the bias voltage, a transistor 7 conducts and provides a signal to operate a Schmitt trigger 21 with a slight delay imposed by capacitors 19, 22 and resistor 20. The output of the trigger 21 renders a transistor 30 conductive to energize the relay 27. The arrangement then functions in the manner described in Specification 1,186,371. |
