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Browse Prior Art Database

Motor Runaway (Overspeed) Detection with Output Averaging

IP.com Disclosure Number: IPCOM000087297D
Original Publication Date: 1977-Jan-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Pisciotta, EC: AUTHOR

Abstract

This apparatus and method enable detection of a motor runaway condition by instantaneously measuring the velocity of the motor during a timed checking interval. In order to measure the motor runaway condition, three distinct circuits are used: (1) velocity check, (2) output gating, and (3) output averaging.

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Motor Runaway (Overspeed) Detection with Output Averaging

This apparatus and method enable detection of a motor runaway condition by instantaneously measuring the velocity of the motor during a timed checking interval. In order to measure the motor runaway condition, three distinct circuits are used: (1) velocity check, (2) output gating, and (3) output averaging.

Referring to Figs. 1, 2 and 3, the velocity check is comprised of an up-down counter to count full tach pulses, input and output gating, and a clock to control operation of the counter.

Full tach pulses are generated by feeding the motor's tach into nontriggerable single shot 10 using timing components (not shown) to create a narrow pulse (30-100 ns) from each rising edge of the tach, thus creating full tach pulses. These pulses are outputted on conductor 12 and are fed via AND circuits 14 and 16 to the count-up and count-down inputs, respectively, of up-down counter 18. The motor forward backward signal which appears on terminal 20 gates the count signal on terminal 12. In the forward mode, the up-down counter will be incremented, and in the backward mode, the up-down counter will be decremented. The counter can only be incremented and decremented while the clock (not shown) is in the minus (negative) state. The up-down counter is cleared when the clock (not shown) returns to its plus state and a signal presented on terminal 22. The output from up-down counter 18 is decoded by decoders 24 and 26 to determine the speed of the motor.

Velocity is determined by the following formula:

(Image Omitted)

Fig. 3 shows three different gating signals which are used...