Know The Protection Regulation G59 In Detail

What is G59?

G59 is the regulation needed to bind the connection between the generator device with the National Grid. The G59 protection is currently running on G59 issue 3, amendment 4. The Ofgem rules for Embedded Generators originate from this regulation. All the administration work is done under the ENA Engineering Recommendation G59, Issue 3, Amendment 4. These regulations will be permanently scrapped after the upcoming G99 regulations. Power generation plants such as Solar, Wind, Combined heat, and power can use G59 as it complements them. A power plant can use G59 if it is generating over 16A per phase as the total outcome. If the plant has low power generating capabilities, then G83 (G83/2-1) is the most relevant for those plants.

Why Test for G59?

The regulation was invented to protect the National Grid. Sometimes the national grid dangerously receives high-voltage electricity from generators. G59 regulations prevent the transfer of energy from any generator to the grid with the authorization of the local electricity authority. The plants need to inform and get permission from the local electricity authority to transfer electricity from generators to the grid.

1. The Purpose of G59

The primary purpose of the G59 relay is to prevent potentially deadly situations due to a generator sending electricity to an isolated circuit. The relay can disconnect the generator automatically from the mains to prevent these situations. The DNO access various other aspects of a potential connection of the generator to the National Grid. Some of them are mentioned below:

Planning – Local Consent & Land Rights
The Existing Network Suitability
Interface Protection Capability
Harmonics, Distortion & Unbalance
Clustering of Installations
Fault Level Contribution
Reverse Power Flow
Voltage Rise & Step

2. Tests Required G59

The G59 is a circuit breaker to the connected circuit in case electricity reaches the programmed limits. It was invented for protection purposes. These tests for G59 are conducted by an independent contractor under the observation of an engineer from the local DNO.

Over Voltage (Stage 1 & 2)
Under Voltage (Stage 1 & 2)
Over Frequency (Stages 1 & 2)
Under Frequency (Stage 1 & 2)
Vector shift
ROCOF (Rate of Change of Frequency)
LOM (Loss of Mains)
Stability test

What is G99 Solar?

G99 has been available in the market for more than three years now. Now every new power generation or storage plant that has ties to the UK electricity network needs to be designed and compliant as per the new recommendations.

These regulations dictate the terms for any in-parallel or synchronized generator device have connections with the mains electrical utility grid (National Grid). The regulation regarding G99 solar panels was invented from Ofgem rules, operated by the Energy Networks Association (ENA).

1. G99 Protection Panels

The connection operator uses G99 panel and G99 feeder panels for various generation schemes for the grid. Each panel is complete with the following components: