Digitallisation implementing method for ac motor heat overload protection

A technology of an AC motor and a realization method, which are applied in the directions of automatic disconnection emergency protection devices, emergency protection circuit devices, electrical components, etc., can solve the problem of inconvenient use, low sampling and operation speed requirements, and high sampling and operation speed requirements. question

Inactive Publication Date: 2008-04-30
HARBIN INST OF TECH
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Problems solved by technology

[0003] In order to overcome the shortcomings of the existing motor thermal overload protection methods that require high sampling and calculation speed of the protection equipment and are inconvenient to use, a kind of AC motor thermal overload protection that does not require high sampling and calculation speed of the protection equipment and is easy to use is provided. method

Method used

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  • Digitallisation implementing method for ac motor heat overload protection
  • Digitallisation implementing method for ac motor heat overload protection
  • Digitallisation implementing method for ac motor heat overload protection

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specific Embodiment approach 1

[0005] Specific Embodiment 1: The present embodiment will be specifically described below with reference to FIG. 1 . The steps of this embodiment are as follows: the motor protection device is powered on, the first step 101; and value, the fourth step 104; every interval time Δt collects the current value of the motor terminal through the current transformer, the second step 102; every interval time mΔt calculates the positive sequence current and negative sequence current of the motor once, the third step 103; judge Whether the positive sequence current is greater than 0.06 times the rated current value I of the secondary side of the current transformer n , the fifth step 105; the result of the fifth step 105 is yes, then judge whether the motor is working within the starting time, the seventh step 107; the result of the fifth step 105 is no, then calculate the interval time mΔt according to the motor stall state The calorific value of the form, the sixth step 106; the re...

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Abstract

The digital method includes following steps: after power on, protector calculates value 1 of formula expressed in the invention; collecting current value at side of electromotor and calculating positive sequence current and negative sequence current; determining whether positive sequence current is larger than 0.06 time of rated current at secondary side of current transformer, and determining states of electromotor: in starting state or in operating state or stop state; calculating formatted heat value in each state respectively; cumulating formatted heat value in each state; determining whether the cumulated value is larger than or equal to value 2 expressed in the invention to decide whether to stop electromotor; after stopping motor, cumulating formatted heat value continuously; determining whether formatted heat value is smaller than value 3 to decide whether to restart motor is allowed. The method reduces quantity of real time computation and required calculation speed.

Description

Technical field: [0001] The invention relates to a digital realization method for motor thermal overload protection. Background technique: [0002] In the traditional implementation method of motor thermal overload protection, the calculation, judgment and protection of thermal overload faults are often carried out by sampling once and calculating once. This method has high requirements on the sampling and calculation speed of the motor protection equipment. The calculation method of the calorific value of the motor is difficult to realize with digital equipment. The protection method involved in the invention adopts the method of sampling multiple times, calculating the formal heat once, and calculating the criterion parameters related to the formal heat before the real-time sampling calculation. This method greatly reduces the real-time calculation amount of the motor digital protection device, lowers the requirement for the operation speed of the motor digital protection...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H7/085H02H5/04
Inventor 佟为明赵志衡李凤阁张文义鄢志刚
Owner HARBIN INST OF TECH
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