The relay model library in PowerFactory does not cover every existing or historical relay on the market, nor every possible configuration. The diversity in relay models and their functionalities is simply too vast. Instead, DIgSILENT prioritises widely requested models and commonly used functions. Moreover, relay models are typically not designed to act as exact “digital twins” of real devices. Rather, they are intended to simulate key functionalities relevant to a user’s specific study—such as overcurrent coordination—without replicating every possible setting in the real relay.

When creating relay models, DIgSILENT follows several guiding principles:

1. We prioritise models and functionality frequently requested by users.

If you notice that a specific relay model or function is missing, we encourage you to submit a request through our support system. While we can't promise a development timeline for every request, it will be considered during planning.

To help us, please include:

• The manufacturer and model name
• The specific relay functionality you’re interested in (e.g. overcurrent, earth fault, differential, distance, etc.)
• Any particular protection characteristics you'd like to model
• The type of study you plan to perform (e.g. static short circuit, RMS dynamic, EMT simulation)

2. We aim to model relay series, not just individual models.

Many relays in a series share core functionalities, with added features in high-end models. Instead of creating a separate model for each variation, we often provide one model that represents the full series. Users can then disable (“set out of service”) any functions not present in their actual device. These models are often denoted using “x” placeholders in the name, e.g. ABB REF 54x, Siemens 7SJ8x.

3. We balance user benefit with implementation cost.

Most users are primarily interested in relay coordination studies. For this reason, PowerFactory relay models and tools are optimised for those purposes—particularly for overcurrent and distance protection coordination. We generally focus on modelling widely-used core functions, rather than niche or optional features.

Some functions that can theoretically be modelled in PowerFactory may nevertheless be omitted because the actual situation they protect is very hard to emulate in a calculation or simulation.

In some cases, limitations within the underlying relay block models prevent exact replication of a relay’s behaviour. Where possible, we approximate the response. Otherwise, unsupported features may also be omitted.

4. Low-voltage circuit breakers and fuses often require user adaptation.

The market for LV breakers and fuses is especially broad, making full coverage in our library impractical. However, because most devices operate on similar principles, existing models can usually be adapted by adjusting characteristic curves and settings.

Helpful resources include:

• Help > Tutorials > Advanced Functions > LVCB Model modification
• FAQ: Modelling Fuses in PowerFactory
  
  
  

Summary: What are your options?

If a required relay model or function is missing, consider the following:

• Explore the library thoroughly

There may be another model (from the same manufacturer or a generic series) that provides the required functionality. Relay series models use an “x” in their name to indicate general applicability (e.g. ABB REF 54x, Siemens 7SJ8x). Sometimes models are located in the folder of an older manufacturer. For example relays which are now manufactured by GE or Schneider, were historically manufactured by predecessors and may be located in the Alstom, Areva or AEG folders.

• Use a model from the “Generic” folder

These are organised by ANSI function number and are designed to cover a broad range of functions and methodologies. They’re highly flexible, with wide setting ranges and multi-method configurations.

• Modify or create a custom relay model

If existing models don’t meet your needs, you can modify one or build your own. Resources include:

• • Help > Tutorials > Advanced Functions > LVCB Model modification
  • Help > Tutorials > Advanced Functions > Create Relay Models
  • Help > Technical References > Models > Protection Devices

You may also find inspiration by examining existing models in the DIgSILENT library.