Capacitor banks

A capacitor bank is a shunt capacitor for power factor correction. It has its own toolbar button and edit panel, and studies and sizing treat it separately from loads.

Adding a capacitor bank

Select the bus the bank connects to.
Click Capacitor bank in the component toolbar. EKX places the bank below the bus and wires it to the bus.
Enter the bank's rating in the edit panel.

A bank has one terminal at the top and is placed and wired like a load. New banks are tagged CAP-001, CAP-002, and so on.

Capacitor bank properties

The two headline fields describe the rating:

Field	Units	Default	Meaning
Rated kvar	kvar	`25`	The whole installed bank at its rated voltage and frequency
Rated Voltage	kV	Connected bus voltage	Follows the connected bus voltage until you enter one

The Equipment tab holds the rest of the bank:

Field	Range	Default	Meaning
Installed Steps	1 to 100	`1`	Number of steps in the bank
Energized Steps	0 to the installed steps	All steps	Steps connected; `0` disconnects the bank
Rated Frequency	50 Hz or 60 Hz	Project frequency	Frequency the kvar rating applies at
Connection	Delta, Grounded wye, Ungrounded wye	Delta	Bank connection
Losses	0 to 100 W/kvar	`0`	Active-power loss; `0` models an ideal capacitor

The Notes tab holds the Description. In service works as it does for other components.

Every edit saves immediately and is one Undo step.

Capacitor banks in scenarios

In a scenario you can change only Energized Steps and In service. The rating and the other fields belong to the base design and are disabled in a scenario. Use scenarios to compare the bank switched in, partly switched in, or switched out. See Scenarios.

How studies use a capacitor bank

Power flow analysis

Power flow models the bank as a fixed admittance. Its output is:

Q = Rated kvar × (Energized Steps / Installed Steps) × (V_terminal / V_rated)²

The bank also draws a small active power of Losses × kvar. With Energized Steps set to 0 the bank gives no output.

After power flow, the bank shows its kW, kvar, current, and output as a percent of the rated output of its energized steps. When the terminal voltage is above 110% of the bank's rated voltage, the bank shows Above 110% rated V and the load flow report lists it under Overvoltage Conditions. See Interpreting power flow results.

Short circuit and arc flash

A capacitor bank contributes no fault current. Short-circuit and arc flash studies leave it out.

Harmonic study

The harmonic study models the bank as a shunt capacitor with the energized steps of each scenario. See Run a harmonic design study.

Sizing a capacitor bank circuit

Auto-sizing and Re-size system size the bank's circuit from its rated current:

I_r = Rated kvar / (√3 × Rated kV)

The rated current covers all installed steps. Energized steps and scenarios do not change it.

Equipment	Sizing rule	Source
Branch conductor	Ampacity at least 135% of I_r	NEC 2026 460.8; CEC 2024 Rule 26-208(1)
Branch breaker or fuse	Smallest standard rating at or above 135% of I_r	EKX default; NEC 460.9 and CEC Rule 26-210 require only "as low as practicable"
Disconnect or load-break switch in the bank branch	At least 135% of I_r	NEC 460.10(3); NEC 460.24(A)(1) above 1000 V; CEC Rule 26-214

The breaker or fuse rule is EKX's default, not a Code minimum. Neither NEC 460.9 nor CEC Rule 26-210 sets a minimum rating, so a lower rating you select (for example 450 A on a 360.8 A bank) is shown as below EKX's default, not as a Code failure. On a CEC project, a selected protection rating above 250% of I_r is a violation of Rule 26-210.

Example: a 300 kvar bank at 480 V has I_r = 360.84 A. 135% of I_r is 487.1 A, so EKX selects a 500 A breaker and a conductor with at least 487.1 A ampacity.

Upstream equipment

A feeder conductor that supplies only capacitor banks needs at least 135% of the banks' summed I_r (NEC 460.8; CEC Rule 26-208(1)).
A bus or protection device that supplies only capacitor banks is proposed at 135% of the summed I_r as EKX's default. A lower rating you select is shown as below that default, not as a Code failure. A disconnect switch that supplies only banks needs at least 135% (NEC 460.10(3) or 460.24(A)(1); CEC Rule 26-214).
In a feeder that also supplies other loads, the banks add nothing and subtract nothing.
A transformer that supplies only capacitor banks is sized to at least 135% of their kvar on a CEC project (Rule 26-220). On an NEC project it is not sized from the banks.

Limits

On an NEC project above 1000 V, EKX does not auto-size the bank's conductor or protection and says: "NEC Article 460 gives no conductor or protection multiplier for capacitors above 1000 V. Select this circuit's cable and protection by hand."
CEC rules apply at every voltage.
A capacitor branch has no voltage-drop target.

Reports and exports

The load flow report has a Capacitor Bank Results table.
The equipment schedule report has a Capacitor Bank Schedule.
The equipment schedule spreadsheet export has a Capacitor Banks sheet.

Projects with capacitor bank loads

Capacitor banks used to be a load type. EKX converted each load whose type was "Capacitor bank" into a capacitor bank with the same name, position, connections, results history, and scenario energized steps.

A converted load that had a capacitor model keeps its rating, steps, connection, and losses.
A converted load without a model became a bank rated at its stored reactive power (or 25 kvar if it had none), at its rated voltage and the project frequency, with a delta connection, one energized step, and no losses.
Scenario values other than energized steps and in service were dropped.

"Capacitor bank" is no longer in the load type list. Reactor remains a load type.

Loads and motors - Generic loads and motors
Understanding power flow - How capacitor banks are modelled
OCPD sizing - Protection device sizing
Read and change project data through the API - The capacitor_bank component type