FAST_LOAD_SHED
Three-stage load shedding on under-frequency with definite-time delays, plus an immediate computed-deficit path, latched until an operator resets.
When to use it
Use FAST_LOAD_SHED when an island can lose more generation than its remaining machines can carry, and interruptible load has to be shed in priority stages — faster than an under-frequency relay scheme can act when the deficit is already known from a breaker status.
Interface
The published port signature. This is the whole of what the block exposes to your program — the implementation body is not shown here and ships with the download.
Inputs
| Port | Type | Unit |
|---|---|---|
| ENABLE | BOOL | — |
| ARM | BOOL | — |
| FREQ | REAL | Hz |
| FREQ_OK | BOOL | — |
| F1 | REAL | Hz |
| F2 | REAL | Hz |
| F3 | REAL | Hz |
| STAGE_DLY | TIME | — |
| IMBALANCE | REAL | kW |
| KW_DEFICIT_TRIP | REAL | kW |
| STAGE1_KW | REAL | kW |
| STAGE2_KW | REAL | kW |
| STAGE3_KW | REAL | kW |
| F_RESET | REAL | Hz |
| RESET | BOOL | — |
Outputs
| Port | Type | Unit |
|---|---|---|
| STAGE | USINT | — |
| SHED_KW | REAL | kW |
| SHED_1 | BOOL | — |
| SHED_2 | BOOL | — |
| SHED_3 | BOOL | — |
| ARMED | BOOL | — |
| DEFICIT_TRIP | BOOL | — |
| RESET_INHIBIT | BOOL | — |
| ALM_SHED | BOOL | — |
| ALM_FREQ_FAULT | BOOL | — |
| ALM_CFG_ERR | BOOL | — |
IEC 61499 event interface
EI INIT, REQ·EO INITO, CNF
Supervised control write
FAST_LOAD_SHED commands a real actuator. It is written to sit underneath your own interlock, permissive and protection logic — not to replace it. Commission it as you would any control block you wrote yourself.
Validation evidence
- Tests
- 10
- Simulated scans
- 279
- Simulator
- v0.1.0
Complete IEC 61131-3 implementation with a published test suite that runs on the vplant simulator. The counts above are that suite, executed on this build.
- Conforms to IEC 61131-3
- Conforms to IEC 61499
Download FAST_LOAD_SHED — free
Create a free Ri Tech account to download the block. You get the Structured Text body, the Rockwell Add-On Instruction (.L5X), the Schneider Control Expert DFB (.XDB), PLCopen XML, the IEC 61499 function block type (.fbt) and the datasheet.
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