MiCOM Protection

20, 30 and 40 Series Relays Key Features

The MiCOM range of relays offers varying levels of functionality and hardware options to best suit the protection requirements, and allows the customer to choose the most cost effective solution for their application.
The 20, 30 and 40 series hardware platforms are the building blocks of the MiCOM protection relay range providing the capability for a wide variety of protection, control, measurement,monitoring and communication functions.
The versatile hardware allows for application in many installations and a common relay management software (MiCOM S1) makes for easy configuration and application.
A standard and simple user interface across the range makes this ideal in any environment, from the more complex bay level control and mimic to the more simple LCD display and interrogation facility.
Numerous integrated communication protocols allow easy interfacing to most substation control or SCADA systems. The majority of MiCOM 30 and 40 series relays can be supplied with ethernet, to allo a full IEC 61850 solution for the substation.


Integrated Generator Protection

Transmission and Distribution
  • Distance Protection
  • Line Differential
  • Transformer Management
  • Busbar Protection
  • Stand Alone Breaker Fail Protection
  • Directional/Non-Directional Overcurrent
  • Feeder Management and One Box Solutions
  • Loadshedding
  • Voltage & Frequency Protection
  • Motor Management
  • Interconnection Protection
  • Feeder Management
  • Transformer Management
  • Management
Customer benefits
  • One single configuration software - MiCOM S1
  • 1A/5A dual rated inputs
  • Scalable hardware
  • Flexible mounting
  • Standardized user interfaces
  • Wide range of communication protocols

The MiCOM range of relays fulfils the requirements at all voltage levels from LV to EHV for Industrial, Distribution and Transmission Systems.

  • 1A/5A dual rated CT's
  • Event and Disturbance Recording
  • Various casing and mounting options
  • Relays have rear RS 485 port with choice of protocols and front RS 232 for local setting
  • A number of auxiliary supply and digital input voltage options
20 Series Relays (Px2x)

It will fulfil the basic requirements of industrial,transmission and distribution systems providing simplicity and ease of application in a wide range of installations.

  • Scalable solutions where type and quantity of protection features is model dependent
  • Simple 'AND' logic equations available on most models
  • Compact hardware options for easy installation
  • Common functions throughout the range
30 Series Relays (Px3x)

Designed to meet the rigorous requirements of MV, HV and EHV systems with particular focus on feeder and transformer protection and control.

  • Protection with Bay level control options to facilitate feeder management
  • Input/Output quantity selectable based on requirements
  • A number of Rear Port hardware options available with a wide range of Protocols selectable via software
  • Protection functions available for unearthed/petersen coil earthed systems
  • Surface and flush mounted as well as compact case option available in the range
  • Full Programmable Scheme Logic
40 Series Relays (Px4x)

It will fulfil the protection requirements for a wide market of MV, HV, EHV and industrial systems and offers a wide range of protection functions.

  • Full Programmable Scheme logic available with Graphic Configuration Tool for easy setting
  • Scalable Input / Output hardware depending on requirements
  • Operating voltage selectable via Software for Opto inputs
  • Hardware accessories available for easy mounting in racks or panels.
Px2x Series

The integrated functions reflect the different requirements in system protection. The preferred applications are as follows:

  • P12x: Universal Overcurrent protection for main or back-up protection on MV and HV systems
  • P22x: Motor Protection Series for LV and MV systems
  • P52x: Line Differential protection for MV and HV systems with multiple communication options
  • P821 : Dedicated Breaker Failure Protection suitable for EHV, HV and MV systems
  • P92x: Voltage and frequency protection suitable for generators, motors and feeders
Px3x Series

30 Series protection devices provide a wide range of protection and control functions meeting stringent market segments. The range is especially suitable for petersen coil earthing requirements.

The preferred applications are:

  • P13x: Feeder management relays suitable for railway, MV and HV systems with various types of earthing practices
  • P43x: Distance protection for MV, HV and EHV systems and rail catenary requirements
  • P63x: Differential protection for transformers, generators and motors (including railway transformers).
Px4x Series

40 Series protection devices provide a wide range of protection and control functions and meets the requirements of a wide market segment.

The preferred applications are:

  • P14x: Feeder management relay suitable for MV and HV systems
  • P24x: Rotating Machine Management relay for application on a wide range of synchronous and induction machines
  • P34x: Generator protection for small to sophisticated generator systems and interconnection protection
  • P44x: Full scheme Distance protection relays for MV, HV and EHV systems.
  • P54x: Line Differential protection relays for HV/EHV systems with multiple communication options as well phase comparison protection for use with PLC.
  • P74x: Numerical Busbar protection suitable for application on MV, HV and EHV busbars
  • P94x: Frequency protection for load shedding, load restoration and generator abnormal detection
Programmable scheme logic

Simple logic equations as well as block logic is available in a number of 20 series relays, see figure 1. Powerful graphical logic available in the 30 and 40 series relays allows the user to customize the protection and control functions of the relay. It is also used to program the functionality of the opto-isolated inputs, relay outputs, LED and user alarms.

The Programmable Scheme Logic can be used to implement additional supervision features, such as trip circuit supervision or implement complex logic such as frequency restoration schemes. Schemes have been developed capable of supervising the trip coil and circuit with the circuit breaker open or closed.

The Px40 gate logic includes OR, AND, NOT and majority gate functions, with the ability to invert the inputs and outputs, and provide feedback. A number of general purpose logic timers are also available as well as those timers used to condition the relay contacts. The system is optimized (event driven) to ensure that the protection outputs are not delayed by the PSL operation.

The Programmable Scheme Logic is configured using the graphical MiCOM S1 PC software, as shown in Figure 2 The Px30 logic can be created using Boolean Equations or a graphical interface as shown in figure 3.

Proframmable scheme logic Sample
Independent Protection Settings Groups

Up to two setting groups are supported in the 20 Series whereas the 30 and 40 series can offer up to four independent setting groups. These can be activated locally, remotely or via a dedicated input and are used to allow for different system operating conditions and where adaptive relaying is applied.

Measurement & Post Fault Analysis

The MiCOM Range of relays are capable of measuring and storing a wide range of system quantities such as Current, Voltage, Frequency, Power etc. depending on the relay functionality.
All event, fault and disturbance records are time tagged to a resolution of 1ms using the internal real time clock and are stored in non-volatile memory. A supervised lithium battery ensures that the real time clock and records are maintained during auxiliary supply interruptions.

Where relays are communicating to a SCADA system, the protocols' telegrams can be used for external time synchronization or alternatively an optional IRIG-B port is available for accurate time synchronization on all Px30 and Px40 MiCOM relays.
Some relays can also use an opto input to synchronize the relay’s clock.

Power System Measurement

A comprehensive set of measurement values including instantaneous and derived values are available on the relays.
These measured values can be displayed on the front LCD display or transferred locally or remotely as per the user requirements.

Event records

These are generated for status changes to logic inputs and outputs, modifications to one or more setting parameters and alarm signals.
All events are time-tagged and stored in chronological order in a cyclic memory where the oldest record is overwritten once the relay's maximum event count is exceeded. These are readily available for viewing on the LCD, or extraction via the communication ports.

Fault records

At least 5 records are supported on all relays and for every fault, the following information is captured in the relay records

  • A fault number
  • The date and time
  • The active setting group
  • The function that issued the trip
  • The magnitude of the current/voltage that gave rise to the trip command
Disturbance records

The internal disturbance recorder will record the sampled values of all analog input variables such as phase currents and voltages etc. where applicable during a fault. Oscillographic analysis can be performed using MICOM S1 which will provide the means to quickly analyse analog and digital signals on the same time-scale for convenience. Disturbance records can be extracted from the relay via the communication ports and saved in the COMTRADE format.


As standard, a front communication port is available for local access to the relay. An auxiliary rear communication port is available as an option on relays providing an engineering port for easy access to settings, records and measurements for protection engineers. A main rear communications port is also available for interface to a SCADA system. A number of protocols are available as an option for this purpose. (See cortec code for each relay)

Proframmable scheme logic Sample