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Protection and Control Devices
for Protection and Control of Voltage Transformer



Digital oscilloscope
Event log


Integration in


Environment temperature


User-defined logics


Microprocessor devices RZL-05.VT are used for relay protection, automation, control, registration and alarm signaling of voltage transformers 110–35–10(6) kV of complete switchgears at power and industrial facilities.

Devices are designed for facilities: distribution networks, transformer substations, stations with guaranteed (AC, DC or rectified voltage) and non-guaranteed operational current.

Devices are to be mounted into relay cubicles of switchgears, relay panels.

Devices have user-defined logics inclusion.

# Download the catalog. Relay Protection and Automation Devices.


  • Complex substation protection by voltage (monitoring and control of voltage transformer VT1 of the first busbar section, VT2 - auxiliary transformer).
  • Operating parameters settings via built-in HMI and PC software tool: functions activation/deactivation, protection stages values and time delay for each stage e t.c.
  • Individual configuration of each photosensor input.
  • Flexible configuration settings.
  • Non-volatile storage of settings, events, fault recordings.
  • Total waveform recording duration 600 s.
  • A solid number of output relays, incl. one reinforced relay for switching high values instantaneous currents, switching in circuits with high inductance, and one bistable relay, eliminating the need to install additional relays.
  • Remote configuration and data transfer including current parameters and function settings, apparatus state, events, measurements via RS-485 interface by MODBUS RTU protocol.
  • Remote control of HV devices via MODBUS RTU protocol.
  • Steel casing.
  • Front side USB interface.
  • Real-time self-supervision.
  • Two switchable setting groups.
  • Two mutually redundant power supply units.
  • Universal AC/DC power supply source.
  • Supply input and all signal circuits are galvanically isolated.
  • Solid overvoltage withstand.
  • Optocoupler-insulated binary inputs.
  • Interredundant hardware and software to improve the reliability of protection, automation functions and data transfering.
  • Presence of digital inputs, controlled by "dry contact", and which saves execution of their functions when switching-off operational power supply.
  • Solid ambient conditions withstand (-40...+55 °C).
  • Multi-lingual LCD interface: English, Ukrainian, Russian.


Protection functions ANSI
Voltage-restrained OCP 50V/51V
Zero-sequence overvoltage protection (3 stages) 59N
Overvoltage protection (2 stages) 59
Undervoltage protection (3 stages) 27
Auxiliary channel overvoltage protection  
Reverse sequence overfrequency protection  
External protection by binary input  
Arc fault protection by binary input  
Overfrequency protection  
Device overheat protection  
Parameter setting groups switch by binary input    activation/deactivation  
Automation functions  
Automatic underfrequency load shedding 81L
Monitoring and indication functions  
Combined undervoltage protection with control of operability of auxiliary channel voltage circuits  
Voltage transformer secondary circuits supervision  
Swithgear bay temperature supervision  
Voltage circuits supervision  

Technical parameters

Power supply units parameters
Operating voltage range, DC or AC 90 – 254 V
Power-on availability time 0,3 s
Operating supply interruption 0,5 s
Independent supply channels (auxiliary voltage circuits) 2
Device burden 8 Wt
Voltage input parameters
Phase voltage 100 V
Number of measurable phases voltages 3
Measured phases voltages range 0,5 – 130 V
Number of measured 3U0 voltage 1
Number of measured line voltage 100 V of VT2 1
Number of measured line voltage 380 V of auxiliary transformer 2
Measured phases voltages range:
  - line voltage of VT2
  - line voltage of auxiliary transformer

1 - 150 V
1 - 570 V
Voltage thermal withstand:
  - continuous    / VT1, VT2
  - continuous    / auxiliary transformer
  - 1 s            / VT1, VT2
  - 1 s            / auxiliary transformer

150 V
400 V
300 V
600 V
Thermal sensor input parameters
Number of inputs 1
Temperature range 0 - 125 °C
PC communication interface USB - 1 pcs
Automated Control System communication interface RS-485 - 2 pcs
Data Protocol MODBUS RTU
Connection speed via USB, RJ-485 9600...38400 bps
Binary input parameters
Number of inputs 12
Rated AC, DC voltage 220 V
Response voltage level 132 - 176 V
Response time not less 40 ms
Current consumption at 220 V:
- power-on current
- continuous

20 mA
4 mA
Maximum voltage, continuous 310 V
Dry contact binary input parameters
Number of inputs 3
Dry contact circuits source voltage DC 24 V
Binary output (relay) parameters
Number of binary outputs 12
AC voltage trip 400 V
Maximum AC current 8 A (16 A for K1 output)
DC voltage trip 300 V
Maximum DC LR-circuit trip current, time constant τ≤20 ms 0,3 A (0,6 A for K1 output)
Mounting type Flush
Device dimensions (WxHxD) 205x240x195 mm
LED indicators total / configurable 20/8
Operating ambient temperature range - 40 to + 55 °C
Maximum Humidity at 25 °C 98 %
Insulation resistance, more than 50 MΩ
Insulation overvoltage withstand,
Instantaneous / continuous
2,0 kV, 50 Hz
5,0 kV pulse
Weight, less then 6,5 kg

RZL-05.VT - wiring diagram

Wiring diagram of external circuits to the devices RZL-05.VT

# Download the catalog. Relay Protection and Automation Devices.