Max PF Capacitor Bank to Keep Resonance Off a Harmonic
The largest PF capacitor bank that keeps the parallel-resonance order at or above a target.
Example
You enter
- Short-circuit power at the bus (MVA) 200
- Target min resonant order (e.g. 4.7 to stay below the 5th) 4.7
You get
- Max capacitor bank 9.054 MVAR
Details, formula, and sources
MVAR_cap = MVA_sc / h^2. A 200-MVA bus targeting an order of 4.7 (to stay below the 5th) caps the bank at ~9.05 MVAR; a bigger bank walks the resonance down onto the 5th. Split into smaller banks or add a detuning reactor for more correction. A screening aid; a harmonic study governs.
MVAR_cap = MVA_sc / h_target^2, the parallel-resonance relation h = sqrt(MVA_sc / MVAR_cap) solved for the bank (the maximum bank that keeps the resonant order at or above the target).
Parallel-resonance order of a power-factor capacitor bank (IEEE 519 / IEEE 1531) solved for the bank, first-principles, by name; a harmonic study governs.
The h = sqrt(MVA_sc / MVAR_cap) resonance relation is a published first-principles result; the bus short-circuit level comes from the system data.
Estimate. AHJ and licensed professional govern.
Field names used by the API: short_circuit_mva, target_resonant_order, max_cap_bank_mvar
- Bank ceiling MVAR_cap = MVA_sc / h_target^2 keeps the resonant order at or above the targetIEEE 1531
- Bigger bank, lower order a larger capacitor bank lowers the resonant order toward the strong low harmonicsIEEE 519
- Idealized ignores load and resistive damping; a detuning reactor or harmonic study is the fixscope of this tile