Digital protection relay for measuring bay
Protection of voltage measuring bay dedicated to be used in MV network protection systems against voltage disturbances and to fulfill Under Frequency Load Shedding automation and Load Restorarion after Under Frequency Load Shedding. The device integrates protection, measuring, control and register functions.

Manuals, diagrams, technical details


Product description

Protection set

27/59 under-/overvoltage, definite-time, three stage, three phase protection (AND/OR operation mode settable)
59N residual overvoltage protection, three stages
47 negative-sequence overvoltage, two stages
27D positive-sequence undervoltage, two stages
81 under-/overfrequency, instantenuous or definite-time, five stages
62 cooperation with external protection


Main features

  • Under Frequency Load Shedding automation
  • Load Restoration after Under Frequency Load Shedding automation
  • Voltage interlocking of frequency-based protection
  • four-inputs (Un=100V) or three-inputs (Un=400V) measuring system
  • different types and variants depending on configuration
  • 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

Energising values are measured input voltages: UL1, UL2, UL3, U0 and calculated values of positive-sequence of three phase voltage (U1), negative-sequence of three phase voltage (U2) and frequency. If one of measured or calculated values exceed the threshold value set by the user, the relay operates according to configuration.

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 voltage Un 100V or 400V
Rated frequency fn 50Hz
Auxilliary voltage 24V DC, 48V – 60V DC,
110V DC/AC, 230V DC/AC
Control voltage acc. to aux voltage
Setting range of threshold values of voltage for 27/27D/47/59 protection functions (0,05÷1,2) Un
Setting range of threshold value of frequency protections (40,0 ÷ 65,0)Hz
Setting range of operating time (0,00 ÷ 99,99)s
Number of underfrequency stages to pick-up UFLS automation 1 ÷ 4
Number of overfrequency stages to pick-up Load Restoration after UFLS 1
Relay response time for „27 / 27D / 47 / 59” protection functions ≤40ms
Relay response time for „59N” protection functions ≤100ms
Accuracy of voltage measuring δ ≤0,5% if U=(0,7 ÷ 1,3) Un
δ ≤1% if U=(0,3 ÷ 0,7) Un
δ ≤2,5% if U=(0,05 ÷ 0,3) Un
δ ≤5% in the rest of measuring range
Accuracy of frequency measuring ± 0,01Hz
Accuracy of time measuring 1% ±10ms
Burden in measuring inputs ≤0,5VA/input
Burden of supply module ≤5W
Thermal withstand of valtage inputs
– continuous 1,2 Un (1,2 U0n)
– short-term (10s) 1,44 Un (1,44 U0n)
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 ~0,7kg
Dimensions (height x width x depth) 75 x 100 x 120mm
Electromagnetic compatibility according to EN 60255-26
Insulation according to EN 60255-5

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