Coal mine underground setting, how to calculate coal mine underground power supply overload setting?

There is overload tuning and short-circuit tuning, and short-circuit tuning is generally two-phase short-circuit and three-phase short-circuit tuning downhole.

Overload setting can be calculated using empirical coefficients, which is more convenient and is usually used.

Short circuit setting is related to power supply distance, cables, transformers, etc., and can only be calculated one by one with formulas.

Work on the correct selection and adjustment of the operating parameters of the relay protection system (device) (the starting value of the fault and the operating time).

Before the electrical equipment is put into normal operation, it is necessary to test the size of the normal operation current of the equipment and whether it is within the setting current range of the superior protection switch. Because there is an objective deviation between the theoretical value of the electrical design and the operating value of the equipment, if the deviation is too large and exceeds the setting value, it will trigger the action of the relay protection equipment, so as to protect the safety of personal equipment.

Including design, installation, tuning, commissioning, operation and maintenance and a series of links, tuning calculation is part of the work, and it is a very important part of the work. Tuning calculation is the analysis and calculation of specific power systems.

The relay warranty of the QBZ protector is set at 660V, and the setting value is twice the click capacity, and at 380V, it is twice the capacity. The setting of the feeder protector requires that the value of the short-circuit current at the end of the line divided by the value of the short-circuit setting value of the feed-in shall not be less than 1140V, and the power multiplied by the time*2.

There is a principle that the calculated current value cannot be greater than the rated current of the motor.

Overload setting corresponds to different switches are different, specifically, 1. Starter overload (overload) setting = load rated current.

2. Total and sub-feed.

Shift secondary side) overload (overload) setting = demand coefficient motor rated current and. 3. Overload setting on the high-voltage side of the transformation = rated current (and) on the primary side of the transformation.

It's too complicated to calculate with a formula, I'll tell you a simple way, if it's 660V voltage, the setting value is: motor power; If the voltage is 1140V: motor power, if the load is large, it can be multiplied.

The setting value of the squirrel cage three-box asynchronous motor is 4-7 times the rated current.

660V three-phase, the empirical formula for the rated current of the motor is power (kw) JDB has an overload delay, and the starting current can be skipped, yes.

It is set to 13A according to the rated current

The empirical formula for the rated current of the 380V motor is power (kw) The empirical formula for the rated current of the 21140V motor is the power (kw) The empirical formula for the rated current of the 6kV motor is the power (kw) The empirical formula for the rated current of the 10kV motor is the power (kw) Therefore, the current setting value of the switch is: 315*

It is normal to have clearances, but only within the standard requirements.

The gap is determined by looking at the volume and the width of the bonding surface, and in between, measured with a feeler gauge.

If you have any other questions, please go to Inquiries.

Calculate the overload current first, i=k p, k is taken according to the voltage, 660V is taken, 1140 is taken. Short-circuit currenti=iqe+ki, and the starting current is generally 6.

According to different mine geology and technical conditions, there can be different coal mining systems and coal mining processes to cooperate, thus constituting a variety of coal mining methods. Such as under different geological and technical conditions.

Longwall coal mining, pillar coal mining or other coal mining methods can be used, and longwall and pillar coal mining methods are very different in terms of coal mining system and coal mining process. It can be considered that the coal mining method is composed of two parts: the coal mining process and the layout of the mining roadway.

Short circuit. There are 4 basic types of short circuits that occur in three-phase systems: three-phase shorts, two-phase shorts, single-to-ground shorts, and two-to-ground shorts.

Among them, except for the three-phase short circuit, the three-phase circuit is still symmetrical, so it is also called symmetrical short circuit, and the other three types are asymmetric short circuits. Ground at the neutral point.

In the power network, the short-circuit fault of one to the ground is the most, accounting for about 90% of all faults. In the power network where the neutral point is not directly grounded, the short-circuit fault is mainly a variety of phase-to-phase short circuits.

Overload current calculation: 660V is generally doubled, for example, a 40kW motor, that is, 40kW

The short-circuit current is generally 4-7 times of the overload current.

The setting formula iz iqe + kx ie (Formula 5) iqe – the starting current of the motor with the largest load capacity carried by the switch.

The starting current of the motor is 4 7 times of its rated current, and it is generally 6 times.

660V System IQE =6IE =6 Pmax (Formula 6)1140V System IQE =6IE=6 Pmax (Formula 7)PMAX - The rated power of the motor with the largest load capacity carried by the switch.

kx - the coefficient is required, the range is 0 1, different loads take different values, you can check the table, and the maximum value is 1 in general.

i.e. – the sum of the rated currents of the remaining motors, a. The calculation method is calculated according to Equation 1 and Equation 2.

The motor does not need to be set, and the switching setting current of the control motor is: 660V, motor power; 1140V, motor power,

Press the protection transformer, such as a high open with a 1000kVA transformer, the high-voltage side of the transformer rated current is equal to 1000 (, set to 58A or 60, short circuit by 3-4 times on it, so the advantage is that there is no need to adjust the setting with the load change.

The setting value of low-voltage equipment in coal mine is calculated as follows: the general empirical formula voltage level is 1140V power * 0.67 = setting value a

660V power * setting value a 380V power * 2 = setting value a This is a general calculation method, and the above calculation method can be selected without knowing the rated current of the motor.

If there is a rated current of the equipment motor, the rated current can be selected directly.

Hope it helps.

According to the different choices of electrical equipment, 1. Low voltage protection:

1. The setting value of overload protection should be greater than the normal working current of the electrical equipment, the rated current of the 380V motor is about 2 times the rated power, the rated current of the 660V motor is about twice the rated power, and the rated current of the 1140V motor is about twice the rated power.

2. The setting value of short-circuit protection is the sum of the starting current of the largest motor + the rated current of the other motors. Starting current: the winding motor is times the rated current, and the squirrel cage motor is 5-7 times the rated current.

2. High voltage protection:

First of all, it is necessary to know the setting current of the low-voltage switch controlled by the high-voltage switch, and the setting current of the high-voltage switch is greater than the setting current of the low-voltage switch controlled by it. The setting current of the upper high-voltage switch is greater than the setting current of the next level switch.

I don't know if I made it clear, I hope it helps you.