MLP-71 Series Multi-functional Microprocessor-based Complete Protection and Automatic Device
Introduction
MLP-71series multi-functional complete protection and automatic device adopt real time multi-task technique, and realizes the setting value, modification and turning on or off by keyboard operation.
It integrates the various protective functions for overhead transmission line and cable line, which is applicable to neutral grounding and neutral insulation (grounding by Petersen coil or not) network of 35-110kV. So this device can be supplied for the main protection of phase to phase and phase to earth faults, otherwise also the backup line protection of 220kV network.
This device also has a good protection ability for the various events that can happen in the power network, such as short circuit through high transition resistance, P.S. that may happen on heavy load lines, and possible harmonic influences that may happen between the alternate and direct coupling power systems.
Main Products
- MLP-71 Distance relay, zero-sequence current directional protection, measurement and control device
- MLP-71(A) current and voltage protections, phase distance relay ,measurement and control device
- MLP-71(B) Distance relay with carrier blocking, zero-sequence current directional protection with carrier blocking, measurement and control device
Functions
| Function | Code | MLP-71 | MLP-71(A) | MLP-71(B) | |
| Protection function | Phase distance with carrier blocking | Y | |||
| Ground distance with carrier blocking | Y | ||||
| Directional zero-sequence current with carrier blocking | Y | ||||
| Current instantaneous tripping | Y | Y | Y | ||
| Voltage instantaneous tripping with current blocking | Y | Y | |||
| Voltage instantaneous tripping with directional current blocking | Y | Y | |||
| Directional undervoltage overcurrent | Y | Y | |||
| Three zone phase distance | Y | Y | Y | ||
| Three zone ground distance | Y | Y | |||
| Four zone directional zero-sequence current | Y | Y | |||
| Automatic device function | Three phase recloser | Y | Y | Y | |
| Backup power throw in | Y | Y | Y | ||
| Two zone underfrequency load share/inter-disconnection | Y | Y | |||
|
Undervoltage inter-disconnection |
Y | Y | |||
| Zero- sequence overvoltage inter-disconnection |
Y | ||||
| Fault locator | Y | Y | Y | ||
| Fault wave recorder | Y | Y | |||
| Events recording | Y | Y | Y | ||
| Control | TV switching for double bus-bars | Y | Y | Y | |
| Three phase C.B.operation | Y | Y | Y | ||
| Measurement | Current, voltage, frequency A,V,f | Y | Y | Y | |
Power, power factor, P,Q,cos |
Y | Y | Y | ||
| Communication interface | ISA communication specification | Y | Y | Y | |
| Events recording | Y | Y | Y | ||
| RS-232C RS-485 RS-422 | Y | Y | Y |
Standard Satisfied
GB15145-94 "General technical specification for microprocessor-based line protection "
GB7261-87 "Basic test method for relay and protective device"
GB6162-87 "Static relay and protective device 's electrical disturbance test"
GB/T14598.9-1995 "Radiation electromagnetic field disturbance test"
GB/T14598.10-1996 "Fast instant disturbance test"
IEC255-22-2:1996 "static discharging test"
GB4856 "Electrical relay's insulation test"
GB/T14598.13-1998 "1MHz pulse group disturbance test"
Technical Parameters
Power D.C voltage:88V~127V,176V~253V
TA secondary rated current:1A or 5A
TV secondary normal voltage: 100/3 V,100V
AC rated frequency:50Hz,60Hz
Output relay contacts: ON-220V,5A continuously
Off -L/R40ms,30WD.C
Engineering Application
It has been successfully used in projects of power plants and power supply companies.