Category: GE

Internal CT secondary monitoring

The CT/VT input modules with enhanced diagnostics are monitoring internal CT circuitry integrity.

This is done to eliminate relay erroneous operation in case of CT secondary winding failure.

The secondary winding of CT is divided into two equal parts with a central tap in the middle.

CT current values from both halves of the CT secondary windings are run through

a differential amplifier to get a true current sample for the phasor calculations.

It also compares between each other by simply summing two samples together.

(Note that due to CT central tap, samples have different polarity.)

In case that values from different halves of the same CT accumulated over

one protection pass per adaptable per signal level do exceed the fixed error boundary,

failure is declared and protection is blocked.

CT secondary monitoring is performed at all four CT channels (A, B, C, and N) individually at each CT

bank.

INTRODUCTION

The performance of a microprocessor-based relay is highly dependent

on the performance of the analog channels measurement of the relay,

as protection functions operate on these values.

The failure of an analog measurement channel, 

either due to a failure in the external measurement circuit,

or due to an internal failure inside a UR CT/VT module, 

can cause incorrect operation of protection functions.

The UR CT/VT modules with Enhanced Diagnostics (module types 8L, 8M, 8N, 8R, 8S, 8V)

can detect the failure of an analog channel measurement due to internal

failures of the CT/VT module, alarm for failure of the module,

and block tripping from any protection function associated with this module.

This feature is available when using firmware 5.20 or later within

the UR family and therefore field-proven since 2006.

A Safer and Cybersecure Substation

Transmitting the instrument transformers´ measurements digitally

through optical fibers eliminates the risk of inadvertent mishandling

of the current and voltage circuits and makes the relay room a safer

work environment, eliminating hazards and reducing the risk of

personnel injury.

To ensure MU360 have all this connectivity in a cybersecure way, it

has been designed according to IEC 62443 and have all capabilities

described by SL2 of this standard, including RBAC, secure boot and

signed firmware.

Reduce the Engineering Effort and Cost

The use of Process Bus with the MU360 drastically reduces the

need for trenches, ducts, glands, cable trays and copper hardwiring,

as the information is exchanged among IEDs using fiber optic cables

and ethernet switches.

Fewer cables to manage also means reduced engineering complexity

as extensive wiring schematics are replaced by standardized

version-controlled configuration files. Future reconfigurations are

automatically documented by the IED configuration tool.

Flexibility

By integrating binary inputs, outputs, and analogue connections into

one box, the MU360 offers a cost-effective solution for a multitude of

bay configurations. Up to two buses and two lines may be monitored

per box with a flexible configuration of up to 224 binary inputs or 140

binary outputs.

Reliable, Interoperable and Future Proof

The MU360 complies with the main standards for digital

substation IEC 61869-9. IEC 61850 edition 2.1 and IEC 61869

13. which guarantees its interoperability and compliance to the

requirements for being the physical to digital interface of modern

digital substations. Furthermore, measurements of each CT/VT

set may be broadcasted in protection and power quality profiles,

allowing multiple Protection, Automation and Control applications

to consume the data without needing extra footprint for acquisition.

Test Modes

IEC 61850 edition 2.1 provides standard mechanisms for testing

purposes, reducing commissioning complexity and allowing new bay

installations without affecting substation operation.

With the test modes in MU360 users can independently configure

mode and behavior of each logical devices allowing then to operate

as: On, Test, Blocked, Test/Blocked and Off.

Secure Switchyard Interface

• IEC61850 dedicated data modelling for Circuit Breakers, Circuit Switches and

Current and Voltage Transformers.

• Process Interface to model, monitor and control devices in the Switchyard

using IEC 61850.

• All connectivity within protected according SL2 of IEC 62443 design.

Newest Standards Compliance

• Robust hardware and acquisition compliant to IEC 61869-13.

• Flexible configuration for multiple IEC 61869-9 sampled values profiles.

• Compliant to edition 2.1 of the IEC 61850-9-2.

Complete and Simple

• Modern, clean, and simple IED Configurator Tool EnerVista Flex 2.0.

• Flexible and complete set of Logical Nodes for Protection, Control and Automation

• Intuitive Interface Digital Substation Projects.

Applications

• Process Interface Unit (PIU) for full bay digitization.

• Standalone Merging Unit (SAMU) for conventional instrument transformers.

• Switchgear Control Unit (SCU) for interfacing and control primary equipment such as

circuit breakers and disconnectors.

• Bay unit for GE B30X distributed bus bar protection system.

• Revenue accuracy and power quality metering applications.

• Breaker-and-a-half line terminals using a single PIU device.

• Two feeders in a single PIU device.

Modular & Powerful

• MU360 stands as a modular device with flexible 40TE or 80TE enclosures,

perfect to be your single process interface in the yard.

• Up to 14 flexible slots for Analog Acquisition (Protection and Measurement) and Binary I/O,

including High Speed High Break.

• Up to 18 CT/VT Interface.

• Several combination options up to 224 Binary Inputs or up 140 Binary outputs.

• A single box for Protection, Control and Automation purposes.

Key Benefits

• Compact form factor supports field installation options into circuit breakers cabinets,

marshalling kiosks and metal-clad switchgear.

• Two slots for CT/VT analog boards supports application on breaker-and-a-half lines, dual

distribution feeders, and combination protection and metering installations.

• 14 slots for I/O cards allows multiple applications. Apply as Merging Unit, Switchgear

Control Unit device or PIU. Right size and point count for all type of application.

• High Speed High Break output contact option to directly operate into Circuit Breakers and

Switchgears.

• Up to 4 SV streams IEC 61869-9/IEC 61850-9-2 Ed 2.1compliants for Protection and

Metering profile.

• Full integration into the digital substation through up to 6 SFP interfaces, support for PRP and

HSR redundancy protocols for availability networks, and IEEE 1588 Precision Time Protocol

• Easy commissioning through simple EnerVista Flex 2.0. simulated Sampled Values and

Test modes controllable per Logical Device to integrate multiple circuit breakers and

disconnectors in one MU360

Your bridge from physical to digital worlds:

Process Interface Unit for Digital Substations

MU360 is the Process Interface Unit (PIU) with analog and binary interfaces for full

switchyard modelling, control and digitization using IEC 61850 and IEC 61869 standards and

protocols such as Sampled Values (SV), GOOSE, MMS and PTP.

The MU360 unlocks the full value of a completely digital substation, capable to be a single

I/O interface for Protection, Automation and Control applications to bay IEDs. Limiting the

field wiring just up to the MU360 reduces project complexity by reducing cabling, terminals,

and physical connections, which combined with a complete set of logical nodes allows

design standardization on the yard. Bay level IEDs can use data from redundant MU360

units, increasing system availability. Bay level IEDs can also be quickly replaced or added

using IEC 61850 test modes as no field wiring is involved. The MU360 has the additional

benefit of improving CT performance and cost through a lower connected burden and a

reduction in the number of CT cores required for an application.

Test Modes

IEC 61850 edition 2.1 provides standard mechanisms for testing

purposes, reducing commissioning complexity and allowing new bay

installations without affecting substation operation.

With the test modes in MU360 users can independently configure

mode and behavior of each logical devices allowing then to operate

as: On, Test, Blocked, Test/Blocked and Off.

A Safer and Cybersecure Substation

Transmitting the instrument transformers´ measurements digitally

through optical fibers eliminates the risk of inadvertent mishandling

of the current and voltage circuits and makes the relay room a safer

work environment, eliminating hazards and reducing the risk of

personnel injury.

To ensure MU360 have all this connectivity in a cybersecure way, it

has been designed according to IEC 62443 and have all capabilities

described by SL2 of this standard, including RBAC, secure boot and

signed firmware.

Reduce the Engineering Effort and Cost

The use of Process Bus with the MU360 drastically reduces the

need for trenches, ducts, glands, cable trays and copper hardwiring,

as the information is exchanged among IEDs using fiber optic cables

and ethernet switches.

Fewer cables to manage also means reduced engineering complexity

as extensive wiring schematics are replaced by standardized

version-controlled configuration files. Future reconfigurations are

automatically documented by the IED configuration tool.

Flexibility

By integrating binary inputs, outputs, and analogue connections into

one box, the MU360 offers a cost-effective solution for a multitude of

bay configurations. Up to two buses and two lines may be monitored

per box with a flexible configuration of up to 224 binary inputs or 140

binary outputs.

Reliable, Interoperable and Future Proof

The MU360 complies with the main standards for digital

substation IEC 61869-9. IEC 61850 edition 2.1 and IEC 61869

13. which guarantees its interoperability and compliance to the

requirements for being the physical to digital interface of modern

digital substations. Furthermore, measurements of each CT/VT

set may be broadcasted in protection and power quality profiles,

allowing multiple Protection, Automation and Control applications

to consume the data without needing extra footprint for acquisition.