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Title: Adjustable electronic load-alarm relay

Abstract

This invention is an improved electronic alarm relay for monitoring the current drawn by an AC motor or other electrical load. The circuit is designed to measure the load with high accuracy and to have excellent alarm repeatability. Chattering and arcing of the relay contacts are minimal. The operator can adjust the set point easily and can re-set both the high and the low alarm points by means of one simple adjustment. The relay includes means for generating a signal voltage proportional to the motor current. In a preferred form of the invention a first operational amplifier is provided to generate a first constant reference voltage which is higher than a preselected value of the signal voltage. A second operational amplifier is provided to generate a second constant reference voltage which is lower than the aforementioned preselected value of the signal voltage. A circuit comprising a first resistor serially connected to a second resistor is connected across the outputs of the first and second amplifiers, and the junction of the two resistors is connected to the inverting terminal of the second amplifier. Means are provided to compare the aforementioned signal voltage with both the first and second reference voltages andmore » to actuate an alarm if the signal voltage is higher than the first reference voltage or lower than the second reference voltage.« less

Inventors:
 [1];  [2]
  1. Paducah, KY
  2. Kevil, KY
Issue Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
OSTI Identifier:
862455
Patent Number(s):
3934239
Assignee:
United States of America as represented by United States Energy (Washington, DC)
Patent Classifications (CPCs):
H - ELECTRICITY H02 - GENERATION H02H - EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
G - PHYSICS G01 - MEASURING G01R - MEASURING ELECTRIC VARIABLES
DOE Contract Number:  
W-7405-ENG-26
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
adjustable; electronic; load-alarm; relay; improved; alarm; monitoring; current; drawn; motor; electrical; load; circuit; designed; measure; accuracy; excellent; repeatability; chattering; arcing; contacts; minimal; operator; adjust; set; easily; re-set; means; simple; adjustment; generating; signal; voltage; proportional; preferred; form; operational; amplifier; provided; generate; constant; reference; preselected; value; aforementioned; comprising; resistor; serially; connected; outputs; amplifiers; junction; resistors; inverting; terminal; compare; voltages; actuate; signal voltage; alarm relay; serially connected; motor current; reference voltage; preferred form; electrical load; preselected value; operational amplifier; reference voltages; voltage proportional; improved electron; selected value; current drawn; /340/327/

Citation Formats

Mason, Charles H, and Sitton, Roy S. Adjustable electronic load-alarm relay. United States: N. p., 1976. Web.
Mason, Charles H, & Sitton, Roy S. Adjustable electronic load-alarm relay. United States.
Mason, Charles H, and Sitton, Roy S. Thu . "Adjustable electronic load-alarm relay". United States. https://www.osti.gov/servlets/purl/862455.
@article{osti_862455,
title = {Adjustable electronic load-alarm relay},
author = {Mason, Charles H and Sitton, Roy S},
abstractNote = {This invention is an improved electronic alarm relay for monitoring the current drawn by an AC motor or other electrical load. The circuit is designed to measure the load with high accuracy and to have excellent alarm repeatability. Chattering and arcing of the relay contacts are minimal. The operator can adjust the set point easily and can re-set both the high and the low alarm points by means of one simple adjustment. The relay includes means for generating a signal voltage proportional to the motor current. In a preferred form of the invention a first operational amplifier is provided to generate a first constant reference voltage which is higher than a preselected value of the signal voltage. A second operational amplifier is provided to generate a second constant reference voltage which is lower than the aforementioned preselected value of the signal voltage. A circuit comprising a first resistor serially connected to a second resistor is connected across the outputs of the first and second amplifiers, and the junction of the two resistors is connected to the inverting terminal of the second amplifier. Means are provided to compare the aforementioned signal voltage with both the first and second reference voltages and to actuate an alarm if the signal voltage is higher than the first reference voltage or lower than the second reference voltage.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1976},
month = {1}
}

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