ABB CM-UFD Grid Feeding Monitoring Relays from LED Controls

LED Controls is proud to supply the ABB CM-UFD, a relay which controls the feed from a renewable energy system into the main grid. If unsafe conditions occur in the grid, the relay automatically disconnects your energy system from the network. This process is known as interface protection. Its purpose is to protect:

• the renewable installation
• electrical equipment
• utility engineers
• the wider electricity network

How ABB CM-UFD relays work

The ABB CM-UFD range continuously monitors:

• voltage
• frequency
• grid stability
• loss of mains conditions

If measurements move outside safe limits, the relay trips and disconnects the renewable system using external switching devices such as contactors or circuit breakers. Once the grid stabilises, the relay automatically reconnects the system after a programmed delay. The relays also include advanced protection features such as:

• Overvoltage and undervoltage
  • Detect when voltage becomes too high or too low for safe operation.
• Overfrequency and underfrequency
  • The UK grid normally operates at 50 Hz. Frequency protection detects major grid imbalances.
• ROCOF
  • Stands for Rate Of Change Of Frequency. It detects sudden frequency changes that often indicate grid faults or loss of mains conditions.
• Vector shift
  • Another method to detect grid instability and islanding events.

What is the G99 Engineering Standard?

G99 is a UK engineering standard issued by the Energy Networks Association (ENA). It defines how generation equipment must behave when connected to the UK grid. The standard ensures that renewable systems:

• disconnect safely during faults
• do not destabilise the network
• reconnect correctly after disturbances
• prevent dangerous islanding conditions

An islanding condition occurs when local generation continues operating after the public grid supply has failed. This can create serious safety risks and equipment damage. ABB CM-UFD models M33 and M33M are specifically designed to meet the requirements of this regulation and are available now from LED Controls.

International CM-UFD Variations

The CM-UFD Range is available in various models accounting for local regulation variations across the globe, and LED Controls can ship any and all models to you, wherever you are!

ABB CM-UFD range comparison

Model	Modbus	regs met	Monitoring functions
CM-UFD.M22	None	CEI 0-21	Over/undervoltage, over/underfrequency, 10 min average voltage, ROCOF, vector shift, interrupted neutral
CM-UFD.M22M	Modbus RTU	CEI 0-21	Over/undervoltage, over/underfrequency, 10 min average voltage, ROCOF, vector shift, interrupted neutral
CM-UFD.M31	None	VDE-AR-N 4110, VDE-AR-N 4120, Belgium C10/11	Over/undervoltage, over/underfrequency, 10 min average voltage, ROCOF, vector shift
CM-UFD.M31M	Modbus RTU	VDE-AR-N 4110, VDE-AR-N 4120, Belgium C10/11	Same as M31 plus Modbus functionality,
CM-UFD.M33	None	G98/1, G99/1	UK preset protection profiles, over/undervoltage, over/underfrequency, ROCOF, vector shift
CM-UFD.M33M	Modbus RTU	G98/1, G99/1	Same as M33 plus Modbus functionality
CM-UFD.M34	None	DEWA DRRG standard	Full multifunction monitoring, advanced redundancy supervision, utility-grade protection
CM-UFD.M34M	Modbus RTU	DEWA DRRG standard	Full multifunction monitoring with advanced redundancy management and Modbus RTU
CM-UFD.M35M	Modbus RTU	VDE 0126-1-1	Full multifunction monitoring, smart-grid diagnostics, advanced digital integration and Modbus functionality

Why choose ABB CM-UFD relays?

As renewable energy systems continue to grow across the world, ABB CM-UFD relay monitoring solutions from LED Controls provide an effective and reliable way to ensure safe grid integration wherever you're based. Check out the range online and get in touch to find out more.