This standard specifies the product classification, technical requirements, test methods, inspection rules, etc. of electronic protectors for flameproof electromagnetic starters for mines. This standard applies to electronic protectors with one or more protection functions that are mainly composed of electronic components in flameproof electromagnetic starters for mines with an AC frequency of 50Hz and a voltage of up to 1140V. MT 175-1988 Electronic protectors for flameproof electromagnetic starters for mines MT175-1988 Standard download decompression password: www.bzxz.net

Ministry of Coal Industry of the People's Republic of China Standard MT175-88
Electronic protector for flameproof electromagnetic starter for mines Published on April 18, 1988
Ministry of Coal Industry of the People's Republic of China
Implementation on July 1, 1988www.bzxz.net
Ministry of Coal Industry of the People's Republic of China
Electronic protector for flameproof electromagnetic starter for mines MT 175--88
Published by China Standards Press
(Beijing Fuwai Sanlihe)
China Standards Press Printed in Qinhuangdao, Guangdong Printing House Xinhua Bookstore Beijing Distribution Office Sold by Xinhua Bookstores in various places Copyright is exclusive and may not be reproduced
Format 880×12301/16
Printing sheet 1
1 Number of words 28000
First edition in February 1989
First printing in February 1989||tt| |Printing 1-2000
Book number: 155066·2-7234
Price 0.80 yuan
Standard 106-54
Ministry of Coal Industry of the People's Republic of China Standard Electronic protector for flameproof electromagnetic starter for mine 1 Subject content and scope of application
MT175-88
This standard specifies the product classification, technical requirements, test methods, inspection rules, etc. of electronic protector for flameproof electromagnetic starter for mine. This standard applies to electronic protectors with one or more protection functions, which are mainly composed of electronic components in flameproof electromagnetic starters for mines with AC 50Hz and voltage up to 1140V. 2 Reference standards
GB1497
Basic standards for low-voltage electrical appliances
GB3836.13836.4 Explosion-proof electrical equipment for explosive atmospheresJB3115 General technical requirements for power system protection, automatic relays and devicesGB2423.4 Basic environmental test procedures for electrical and electronic productsTest Db: Alternating damp heat test methodGB1498
GB6162
GB3797
Protection levels for motor and low-voltage electrical enclosures||t t||Electrical interference test of static relays and protection devicesElectrical control equipmentPart 2Electrical control equipment equipped with electronic devicesGB998
Basic test methods for low-voltage electrical appliances
3Terms and symbols
3.1Hot state
For motors, it refers to the state after the temperature rise of each part of the motor running under rated load for a long time reaches a stable state; for electronic protectors, it refers to the state in which all links of the electronic circuit of the electronic protector reach a stable state through the setting current or a special current on the primary side.
3.2Cold state
For motors, it refers to the state in which the temperature rise of each part of the motor is zero when the motor is not running; for electronic protectors, it refers to the state in which all links of the electronic circuit of the electronic protector reach a stable state when the primary side does not pass current. 3.3Heat accumulation coefficient c
When the motor is working, the heat generated by various losses cannot be completely dissipated immediately when the motor stops working, which is called the heat accumulation effect of the motor. In order to describe the ability of the electronic protector to simulate the heat accumulation effect of the motor, the heat accumulation coefficient is defined and calculated according to formula (1): =t,
×100%
Where: t---3 times the overload action time measured in the cold state, s: t---3 times the last action time of intermittent overload, S, the measurement method is shown in the description of 6.3.6. 3.4 Leakage lockout protection
Before power is supplied, use additional DC power supply and other methods to detect the insulation resistance between the three-phase power supply line and the motor winding to the ground. When the insulation resistance value drops to the specified value, the flameproof electromagnetic starter will not be able to close the switch and supply power. 3.5 Automatic reset
After the electronic protector takes protective action, as long as the fault causing the protective action disappears, the electronic protector can be restored to its original state immediately or after a certain delay. This is called automatic reset. 3.6 Power-off reset
The electronic protector cannot be reset automatically. The power supply of the electronic protector must be interrupted for a certain period of time before it can be restored to its original state. This is called power-off reset.
3.7 Manual reset
The electronic protector cannot be reset automatically. A specific button or switch dedicated to reset must be pressed or toggled before the electronic protector can be restored to its original state. This is called manual reset. 3.8 Broken line (phase) overload protection
When a motor has a broken line (or a broken phase) in the power supply line, if the current of the unbroken line (phase) increases to more than the rated value, the broken line (phase) protection is achieved by detecting this overload signal, which is called broken line (phase) overload protection. 3.9 Broken line (phase) fault detection protection
When a motor has a broken line (or a broken phase) in the power supply line, the broken line (phase) current is detected as zero, which is called broken line (phase) fault detection protection. 3.10 Unbalance protection
When the motor has a three-phase power supply line current imbalance (or three-phase winding current imbalance) that reaches a certain level, protection is implemented, which is called unbalance protection.
4 Product classification
4.1 Electronic protectors should have one or more of the following protection functionsa.
Motor overload protection;
b. Short-circuit protection for motors and their power supply lines; Motor disconnection (phase) overload protection or disconnection (phase) fault detection protection or unbalance protection;c.
Leakage lockout protection for power supply lines and their motors;e.
Other protections.
4.2 The specifications of electronic protectors should be compatible with the rated values ​​of the flameproof electromagnetic starters they match. 4.2.1 The maximum set current value of the electronic protector should be equal to or greater than the rated current value of the flameproof electromagnetic starter it matches, and the preferred series values ​​are 400A; 315A; 200A; 100A; 40A. See Table 1 for the priority recommended values ​​of the setting current grading of electronic protectors. Protector
Series value
MT175-88
For electronic protectors with continuously adjustable setting current, the ratio of the maximum to the minimum setting current value shall not be less than 4, and the total number of electronic protectors with intermittent adjustment of setting current shall not be less than 20, and the ratio of each current setting value to the adjacent lower current setting value shall not be greater than 1.15. 4.2.2 The rated voltage allowed for the electronic protector is equal to the rated voltage of the flameproof electromagnetic starter it matches, and its series value is 127V; 380V; 660V: 1140V
The recommended series value of the power supply voltage of the electronic protector is AC 24V; 36V; 42V. DC ±12V; ±15V; 24V. The basic structure of the electronic protector is divided into two categories:
Integral type: The main body of the electronic protector is one piece, including sensor components such as current transformers, electronic plug-ins that complete various protection functions, power supplies, etc.
b. Combined type: The main part of the electronic protector consists of two or more parts. Technical requirements
5.1 Working conditions and installation conditions
5.1.1 Working conditions
Altitude shall not exceed 2000m.
Ambient air temperature:
The maximum ambient air temperature is divided into two levels, listed in Table 2; Table 2
The minimum ambient air temperature is -5℃.
The relative humidity of the ambient air shall not exceed 95% (+25℃). The pollution level is level 3 as specified in GB1497.
There should be no significant shaking and impact vibration in the workplace (when there are impact and vibration requirements, the user shall negotiate with the manufacturer). The voltage fluctuation of the power supply of the electronic protector shall not exceed the range listed in Table 3. 3
Maximum voltage
Minimum voltage
In the table: U. is the rated value of the power supply voltage of the electronic protector. 5.1.2 Installation conditions
MT175--88
5.1.2.1 Normal installation conditions shall be in accordance with the manufacturer's instructions. If there are requirements for the installation orientation or the performance is significantly affected by the installation conditions, it shall be clearly specified in the instructions.
5.1.2.2 Installation category (overvoltage category): The integral electronic protector shall be Class II as specified in GB1497; the electronic plug-in part of the separately installed combined electronic protector shall be Class 1.
5.2 Protection characteristic requirements
The protection functions of the electronic protector shall comply with the technical requirements specified in this article respectively. If it has protection functions other than those specified in this article, the corresponding technical requirements and test methods shall be separately specified in the product technical conditions. 5.2.1 Overload protection characteristics
5.2.1.1 The protection characteristics of the electronic overload protector used for general flameproof asynchronous motor winding overload protection are shown in Table 4. Table 4
actual current
set current
long term no action
ti.s<3min
t≥5s
No action for a long time
5min
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