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Relay Protection Device for 6–35 kV Distribution Networks.
Reliable and Economic Protection of Power Networks




A wide range of protection
and automation functions


Combined power supply
including CT circuits unit


Backup trip via CB
current solenoids


Digital oscilloscope
Event log


Integration in


Environment temperature


User-defined logics


New multifunctional relay protection and automation devices RZL-05.S series are designed to protect lines from short circuits and earth faults and do not require an external auxiliary power source. These devices can be used as primary or backup protection in medium and high voltage power systems.

# Download the catalog. Relay Protection and Automation Devices.


  • Substations and utilities equipped with medium-voltage switchgears 6-45 kV;
  • Redundant protection of medium / high voltage transformers;
  • Replacement of electromechanical and microelectronic relays and relay protection and automation devices manufactured using outdated technologies (especially when integrating them into SCADA systems).


  • Universal power supply (AC, DC, powered by current circuits);
  • Buttons on the front panel for operational control of circuit breaker;
  • Free programming of digital inputs, outputs, LEDs;
  • Preservation of full performance during prolonged power interruptions;
  • Three data transfer interfaces: USB, RS-485, Ehternet (RJ-45) (option);
  • Unified software "Monitor-2";
  • Integration with existing communication protocols and the possibility of upgrading communication channels in the future;
  • Good price-functionality ratio.

Communication and Interfaces

Devices of RZL-05.S series has three built-in communication ports, of which one RS 485 is a traditional serial interface for the Modbus RTU protocol, and the second is a serial port designed for exchanging information based on Modbus TCP network Ethernet. Ethernet TCP network allows fast data transfer between the central computer and devices, it is effective for downloading waveforms and measurement results. The third SPI port can be used to expand the number of inputs and outputs of the device (up to 128), as well as for the possibility of connecting various digital sensors (temperature, pressure, etc.)

Event Recording and Oscilloscope

The RZL-05.S device memory contains 256 event records, namely: turning the device on and off, changing the status of inputs / outputs, starting and operation of all functions, operation of output relays, device reset, remote control signals. You can use USB port or other available serial ports to download event records to a computer. Event records are stored in non-volatile memory, all events have time stamps with an interval of 10 ms.

The device provides a record of waveforms of emergency processes:

  • instantaneous values of phase currents IA, ІВ, IС;
  • instantaneous values of zero sequence current 3І0;
  • instantaneous values of phase (linear) voltages UА, UВ, UС (UАВ, UВС, UСА);
  • instantaneous zero sequence voltage 3U0;
  • state of discrete inputs and output relays.

Each waveform is linked to the device internal timer with a resolution of 1 ms. The total waveform recording time is set to 30 seconds, the duration of the waveform recording can be configured. The oscilloscope starts by the protection operation, by an external input signal or by automatic control system. All digital and analog information is stored in non-volatile memory. Waveform files are read in Comtrade format.

Тechnical parameters

Power supply units parameters
Rated supply voltage 110, 220 V DC/AC
Power-on availability time 0,25 s (Urated = 220 V)
0,2 s (Urated = 110 V)
Operating supply interruption 0,5 s (Urated = 220 V)
0,2 s (Urated = 110 V)
Device burden 5 Wt (Urated = 220 V)
3 Wt (Urated = 110 V)
Supply from current transformer circuits (optional) 2
Current withstand, continuous/1 s 2,5–10,0/250 А
Current input parameters
Rated input current 5 А
Line current inputs number 3 (2)
Measurable current range 0,2–130,0 А
Measurable current circuits thermal withstand, continuous/1s 15/400 A
Thermal withstand in case of power supply from current circuits, continuous/1s 10/250 A
Rated zero-sequence input current 3I0 1 A
Measurable current range 0,01-4,00 A
Current circuit 3I0 thermal withstand, continuous/1s 5/100 A
Voltage input parameters
Phase voltage 100 V
Number of measured voltages 4 (UA, UB, UC, 3U0)
Measured voltage range 5–200 V
Measurable voltage circuits thermal
withstand, continuous/1 s
150/260 V
Binary input parameters
Number of inputs (optoisolated) 5 (2)
Rated AC, DC voltage 220 V
Response voltage level 132–176 V
Dry contact binary input parameters
Number of inputs 3
Dry contact circuits source voltage DC 30 V
Binary output (relay)parameters
Number of binary outputs 6
AC voltage trip 24–400 V
DC voltage trip 24–300 V
Maximum AC current 8 А
Maximum DC LR-circuit trip current τ≤20мс 1/0,3 A
Communication interfaces USB, RS-485
Ethernet (RJ45)
Data Protocols Modbus RTU
Modbus TCP
Connection speed via USB, RJ-485 9600...115200 bps
Device dimensions (WxHxD) 220х145х100 mm
Indicator 2x16 OLED
Operating ambient temperature range -40...+60 °С
Maximum Humidity at 25 °C 98 %
Insulation resistance, more than 50 MΩ
Weight, less then 4 kg

Embodiments of a device RZL-05.S

Code name Phase voltage measurement inputs Power supply from current circuits Bypass current circuits
RZL-05.S-1 - - -
RZL-05.S-2 - + -
RZL-05.S-3 - + +
RZL-05.S-4 + - -
RZL-05.S-5 + + -
RZL-05.S-6 + + +


Functions ANSI RZL-05.S -
1 2 3 4 5 6
Backup power supply functions
Powered by current circuits (phases of current transformer A and C)      
Backup trip coils via CB current solenoids          
Protection functions
Overcurrent protection (OCP) 50/51
OCP with voltage blocking 51V      
OCP blocking by binary input 50/51  
Switch on to fault high-speed protection 50HS
Logic Selectivity Busbar protection 68
Zero-sequence OCP (unidirectional earth-fault protection) 50N/51N
Directional ground-fault protection (directional zero-sequence power protection) 67N
Overvoltage protection 59      
Undervoltage protection 27      
Zero-sequence overvoltage protection (optional) 59N
Phase conductor break protection (negative sequence or negative to positive sequence ratio current) 46BC
OCP/zero-sequence OCP stage activation by binary signal (current-restrained intertrip)  
Automation functions
Auto-reclosing 79
HV Breaker failure back-up 50BF
Monitoring and indication functions
Trip alarm 30
Internal malfunction alarm 30
Warning alarm 30
Service functions
Non-volatile memory event log  
Non-volatile memory oscilloscope recorder with 30 s total record duration  
Oscilloscope on binary input activation  


RZL-05.S - dimensions

# Download the catalog. Relay Protection and Automation Devices.