MV power line protection
mZAZ-L relay is dedicated to be used as protection of MV lines. The device integrates protection, measuring, control and register functions. The relay can be used in MV network and other level of voltage as well.

Manuals, diagrams, technical details


Product description

Protection set

50/51 instantenoues/definite-time, three-stages, three-phase overcurrent protection
51 inverse-time overcurrent protection
50N/51N ground overcurrent, definite-time, two-stages protection
51N ground overcurrent, inverse-time protection
21N admittance-based ground fault protection
67N directional ground overcurrent protection
59N residual overvoltage protection
62 external protection
79 auto-reclose automation

Main features

  • 4 measuring inputs (IL1, IL2, IL3, U0)
  • Auto-reclose automation
  • 4 setting banks
  • measurment of analog input values
  • real time clock
  • event recorder with capacity up to 500 records
  • last disturbance parameters recorder
  • samples or magnitudes of disturbance and logic states recorder
  • Tripped currents counter
  • Two binary inputs for cooperation with external protection purposes, possibility to be used as blocking inputs
  • Trip impulse
  • alphanumeric LCD display (2×16) and six buttons enabling operation of the relay
  • visual indication (by LED diodes) of pick-ups and trips, exceeding of counters or proper operation of relay
  • 7 programmable relay outputs (S1-S7)
  • RS-485 port for communication with PC computer or supervision and control system (MODBUS-RTU protocol)
  • self-test system of proper operation of relay control
  • enclosure construction enables three types of mounting: 35 mm rail, surface mount or flush mount

Communication interface provides measured and calculated electrical values, binary inputs and outputs states and saved records. The manufacturer provides PC software allowing to set the relay, confirm signals, graphical display of measured values and browse records.


Rated measuring current In 5A
Rated measuring voltage 100V
Rated frequency 50Hz
Auxilliary voltage 24V DC, od 48V do 60V DC,
110V DC/AC, 230V, DC/AC
Control voltage acc. to aux voltage
Setting range of threshold value of voltage in 59N protection 0,05…1,20 Uon
Setting range of current threshold values
– 50/51 protection functions 0,2…30 In
– 50N/51N def.time protection functions  5…500mA or 50…5000mA
– 50N/51N inv. time protection functions 5…100mA or 50…1000mA
Setting range of 67N protection function
– current threshold value 5…100mA or 0,05…1,00A
– voltage threshold value 0,01…0,99 Uon
– characteristic angle 0…90° – cap.
Setting range of 21N protection function
– admittance threshold value 0,05…50,00mS or 0,5…500mS
– voltage threshold value 0,01…0,99 Uon
– characteristic angle 0…90° – cap.
– direction from the busbars
to the busbars
Setting range of sum of tripped currents counter 1…65000 In
Setting range of operating time  0…99,9s
Relay response time for 50/51 protection functions ≤40ms
Relay response time for ground protection functions ≤100ms
Accuracy of current inputs 1%
Accuracy of voltage input 0,5%
Accuracy of time measuring 1% ±10ms
Burden in measuring inputs ≤0,5VA/input
Burden in supply module ≤6W
Thermal/dynamic withstand of current inputs 80In /250In
Continuous/thermal withstand of voltage input 1,2 Uon/1,44 Uon
Relay outputs data:
Max. breaking capacity by 250V DC
– resistive load 0,3A
– inductive load of L/R ≤40ms 0,1A
Max. breaking capacity by 250V, 50Hz
– inductive load, cosϕ=0,4 3A
Continuous contact carry 6A
Ambient temperature (253÷328)K/(-20÷55)°C
Relative humidity ≤80%
Ingress Protection degree IP40
Weight ~0,8kg
Dimensions (height x width x depth) 75 x 100 x 120 mm
Electromagnetic compatibility acc. to PN-EN 60255-26
Insulation according to PN-EN 60255-5

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