Grid codes require that a distributed inverter disconnect quickly if it finds itself powering an "island" — a section of the local grid that's become isolated from the wider utility supply, with the inverter's own output the only thing keeping it energised. Proving that an inverter's anti-islanding protection actually works means recreating that condition on the bench, safely and repeatably, without waiting for a real grid fault. That's the specific job of Preen's ARLC series — an automated RLC load bank purpose-built for anti-islanding test.
What Anti-Islanding Testing Requires
Anti-islanding test procedures, most notably IEEE1547.1-2020, work by balancing a local RLC (resistive-inductive-capacitive) load against an inverter's output so that, when the utility connection opens, the local load and the inverter briefly appear to be in near-perfect equilibrium — the worst-case condition for detecting an island, since there's little frequency or voltage disturbance to trigger a naive detection scheme. The ARLC series exists to build and hold that precisely balanced load condition on demand, then release the utility-side connection in a controlled, repeatable sequence so the inverter's actual detection and trip response can be measured against the standard's required trip time.
Simulating a Range of Load Conditions
The ARLC series can simulate a variety of different load conditions to correspond to realistic islanding scenarios, spanning resistive, inductive, and capacitive load ranges independently rather than as a fixed bundled load. That independent R/L/C control is what lets a test program step through the range of quality-factor and resonant conditions the standard requires, rather than testing only a single worst-case balance point. Through those simulations, the ARLC series confirms that an inverter's anti-islanding protection stays active and effective under the critical, near-balanced conditions that are hardest to detect — not just under an obvious, heavily unbalanced fault.
| Model | Role |
|---|---|
| ARLC-30 | Entry-tier automated RLC load bank |
| ARLC-60 | Mid-tier automated RLC load bank |
| ARLC-120 | High-tier automated RLC load bank |
| ARLC-250 | Top-tier automated RLC load bank |
System Interfaces for Automated Test Sequences
The ARLC series is built to run as part of an automated sequence rather than as a manually-tuned standalone load bank. It provides dedicated system interfaces for Solar Inverter Control, RLC Load Control, and the Anti-Islanding Test sequence itself, which lets a test program step through balance conditions, trigger the island event, and log the inverter's trip response without an operator manually re-tuning the load between runs. That matters for compliance testing in particular, where a program typically needs to repeat the same test across many balance points and log results consistently enough to stand behind in a certification report.
Flexibility and Expandability
Beyond raw simulation capability, the ARLC series is built with flexibility and expandability as a deliberate design goal — the load bank isn't a fixed-configuration test fixture but a platform that can be reconfigured as test requirements change, whether that's a new inverter product line, a different regional grid code, or a research program probing islanding behaviour beyond what a standard compliance test requires. Paired with a PAS or PFV series regenerative grid simulator standing in for the utility connection and a PV-emulating DC source such as the ADG+ series, the ARLC series completes a full anti-islanding test bench without needing custom-built load hardware.