Application of MDS series microcomputer motor prot

Application of MDS series microcomputer motor protection in water source well monitoring

1 preface

using the latest automation technology to monitor water source wells has increasingly become a trend. The general water source well monitoring is realized by PLC + transmitter. The main monitoring objects include:

· three-phase voltage and current of the water pump, as well as the start and stop status of the water pump

· remote start and stop control of water pump

· liquid level, outlet pipe pressure and flow of water source well

the transmitters or sensors used include: three-phase voltage converter, three current transmitters, flowmeter, pressure transmitter and liquid level sensor

water source well monitoring using MDS series micro motor protection + transmitter, the main monitoring objects include:

· three-phase voltage, three-phase current, three-phase active power, three-phase reactive power, power factor, integral electricity, zero sequence current, cross sequence current and other electrical parameters of the water pump

· detection of the start and stop state of the water pump

· over current protection, imbalance (negative sequence overcurrent) protection, grounding (zero sequence overcurrent) protection, too long starting time protection, locked rotor protection, inverse time limit overload (thermal overload) of the water pump. Its main features are: ① single 5V power supply protection, undervoltage protection, overvoltage protection, temperature protection, motor thermal model protection, fault diagnosis

· remote start and stop control of water pump

· liquid level, outlet pipe pressure and flow of water source well

· it can be used in frequency conversion environment

the transformers or sensors used include three-phase current transformers, flow meters, pressure transmitters, and liquid level sensors

compare the two schemes. The latter scheme has the following advantages:

· because the advanced algorithm

is used for direct measurement, three-phase voltage transmitter and three-phase current transmitter are not required, which reduces the cost. Reduce wiring and facilitate installation

· powerful, comprehensive measurement and protection functions ensure the reliable operation of the water pump,. And remote maintenance

2 system structure (taking mds-1 as an example)

3 brief introduction to the protection function of MDS series micro motors:

(1). The function of mds-1 microcomputer motor protection

· without voltage, current and other transmitters, the three meter method directly and accurately measures three-phase AC voltage, three-phase current, three-phase active power, three-phase reactive power, frequency, power factor, zero sequence current, negative sequence current, zero sequence voltage, negative sequence voltage The electric parameters such as integral electric degree can be used in the environment of frequency converter

· it has 3 independent switch relay outputs, which can be used as remote control, tripping or alarm

· 6-way switching value diaphragm input, which can also be used as pulse input

· 2 DC inputs (MA or V), which can be connected to various transmitters

· two way isolation 232 or 41 Specification a. the maximum allowable load of the machine is 10 tons, and the 85 communication interface supports Modbus protocol

· FFT algorithm can calculate 0-31 harmonics

· inverse time limit overload (thermal overload) protection, unbalance (negative sequence overcurrent) protection, too long starting time protection, locked rotor protection, grounding (zero sequence overcurrent) protection, undervoltage protection, overvoltage protection of three-phase asynchronous motor

· three phase motor rotor bar breaking, bearing damage, insulation monitoring and other fault diagnosis functions

· working temperature: - 20 to 70 ℃

· EMC performance is as follows:

(2). Mds-104 microcomputer motor protection function

· no voltage, current and other transmitters are required. Three meter method measurement accurately measures three-phase AC voltage, three-phase current, active, reactive, frequency, power factor, zero sequence current, negative sequence voltage and other electrical parameters, and the data refresh speed is 100 times/s. The measured data can be refreshed 25 times/s, which can also be connected to the two meter method. Under the two meter method, negative sequence protection cannot be carried out

· it has 4 independent switching value relay outputs, which can be used as 2 The inlet holes of wire trunking, cable tray, distribution cabinet, various electrical appliances, etc. shall be tightly blocked for remote control, tripping or alarm

· 6-way switching value diaphragm input, which can also be used as pulse input

· 4 isolated DC inputs (MA or V), which can be connected to various transmitters

· 2-way rs232/rs485 communication interface, supporting Modbus protocol

· overcurrent protection, unbalance (negative sequence overcurrent) protection, grounding (zero sequence overcurrent) protection, too long starting time protection, locked rotor protection, inverse time overload (thermal overload) protection, undervoltage protection, overvoltage protection, temperature protection, motor thermal model protection, fault diagnosis, etc. of three-phase asynchronous motors

· three section overcurrent protection, inverse time speed limit protection, automatic reclosing

· through the calculation of positive sequence and negative sequence current, we can know whether the current motor is rotating forward or reverse, so as to prevent the motor from burning out due to phase sequence error caused by electrical accidents

· working temperature: - 40 to 70 ℃

· EMC pay attention to turning off the main motor source energy as follows:

4 Conclusion

MDS series microcomputer motor protection has more than 2000 sets of products running stably all over the country, including water source well control, pumping unit control and other applications. It is an ideal choice for system integrators. (end)