Hitec Instruments provides a G100-compliant export limitation system based on PRO Series meters, controlling power at the grid connection point.
The response time is not fixed. It is set during commissioning to match how the equipment on site actually behaves, within G100 limits.
The solution is designed to operate safely under all conditions.
The Hitec Instruments solution implements this through built-in fail-safe mechanisms:
The system retains memory of events following a power cycle. All counters/timers, and flags associated with the G100 logic are stored in non-volatile memory, so they are not affected by loss of supply.
In line with the fail-safe requirements, a loss of power will result in the relays operating, meaning both the generation and controllable load ACBs will trip. Once power is restored, the ACBs can be recharged and the system returned to service.
The system retains the full state history. For example, if there have already been two excursions into State 2 within a 24-hour period, any further excursion after power is restored will still trigger State 3, as per G100 logic.
Similarly, if the system enters State 3, the mandatory 4 hours lockout period is preserved. Power cycling the device does not reset this counter/timer and the remaining lockout time continues from where it left off.
All key events, including State 2 excursions, transitions to State 3, loss of communication and power interruptions, are logged within the device for traceability and analysis.
The Hitec Instruments solution is built around PRO Series meters (EM235 / PM335), combining measurement and control within a single device.
The meters measure real-time active power (kW) and direction (import / export) and host the embedded PLC where the control logic runs.
MEL / MIL setpoints, timers and logic conditions are configured inside the meter, and the same device executes relay outputs via DI/DO modules.
This removes the need for a separate external controller.
How the control logic works
The control logic is implemented inside the PRO Series meter using embedded PLC functionality.
Measured power is continuously compared against configured limits (MEL / MIL) using setpoints, logic conditions and timers defined within the device.
The logic is defined using:
The timing behaviour is defined by configurable delays.
If the limit remains exceeded beyond the configured delay, the meter sends a relay signal to reduce generation or adjust controllable loads, bringing the power flow back within the agreed limit.
Control is applied directly to generation, storage or controllable loads through relay outputs.
The logic runs inside the device, so operation does not depend on SCADA or external control systems.
This ensures that control follows actual equipment behaviour and remains within G100 response time requirements.
The control logic is configured using dedicated software, allowing setup of MEL / MIL limits, timing parameters and logic conditions.
During commissioning, delay times can be fine-tuned to match the actual response of inverters, BESS or controllable loads on site.
The solution supports testing in line with G100 requirements, allowing system behaviour to be verified under defined conditions.
Event logs and measured data are available for analysing operation and confirming performance.
After commissioning, the logic runs inside the meter, without the need for continuous software operation.
The Hitec Instruments solution measures active power in real time at the point of connection and controls generation, storage and controllable loads directly, keeping export and import within agreed MEL / MIL limits without external control systems.
