IEC 61921 APFC Panel: What the Standard Means
An IEC 61921 APFC panel in Saudi Arabia is a low-voltage power factor correction bank designed to the IEC product standard for such banks, alongside IEC 61439 for the panel assembly. The standard sets expectations for capacitor ratings, protection, discharge and temperature, so your supplier should state which clauses it meets.
What you receive: a written proposal listing the standards the panel is built and tested to, with scope, lead time and price, within one working day of receiving your bill or specification. Request a quotation
By Eng. Ahmed Ali, Saudi Power Factor Company. Published 9 October 2026.
What does IEC 61921 cover?
IEC 61921 is the product standard for low-voltage power factor correction banks. Treat the table below as a map of how it fits with the other standards on a typical panel. Check the exact clauses in the current edition before quoting them in a specification.
| Standard | What it covers on an APFC panel | Who it concerns |
|---|---|---|
| IEC 61921 | The correction bank as a unit: ratings, protection, discharge, temperature category | Panel designer and specifier |
| IEC 61439-1 / -2 | The low-voltage assembly: busbars, short-circuit strength, temperature rise, dielectric tests | Panel builder, consultant |
| IEC 60831 | Shunt capacitors for AC systems up to 1,000 V | Capacitor manufacturer |
| IEC 60947-4-1 | Contactors used to switch the capacitor steps | Component selection |
| IEC 60529 | Degree of protection of the enclosure (IP code) | Site conditions |
We build in Dammam to the main IEC standards and issue a factory test record with each panel. Your specification decides which of these must appear on the drawings and the data sheet. If the specification names only IEC 61439, say so in your enquiry, and we will show in the proposal how the capacitor bank itself is covered as well.
How does an IEC 61921 APFC panel relate to IEC 61439?
IEC 61439 covers the whole assembly, and IEC 61921 covers what is specific to a capacitor bank. A panel can satisfy IEC 61439 for its busbars and enclosure and still be badly designed as a capacitor bank if its capacitors run hot or its protection is wrong. A consultant who specifies both is asking the supplier to prove both.
In practice, ask your supplier to confirm three things in writing: the standard each part is designed to, the tests performed at the factory, and the ambient temperature the design assumes. Our APFC panel scope lists them in one table.
Worked example: what the standard means for one 50 kVAr step
The numbers are assumed, to show the reasoning on one step. Your project values will differ.
Take a 50 kVAr step on a 380 V three-phase supply.
- Rated current: 50,000 ÷ (√3 × 380) = about 76 A.
- Allowance for overcurrent: capacitors are expected to tolerate a continuous current above rated, commonly 1.3 times. That gives 76 × 1.3 = about 99 A. Conductors, fuses and contactors are chosen above 99 A, not 76 A.
- Detuning: with a 7% reactor, the capacitor sees a higher voltage than the supply. 380 ÷ (1 − 0.07) = about 409 V. A capacitor rated 440 V or higher is therefore chosen for the step, and a 400 V capacitor is not suitable.
A panel specified only by kVAr hides all three decisions. A panel specified to the standard shows each one on the drawing. Read more on the reactor choice in detuned capacitor banks.
What should you ask a supplier to confirm?
Use this list when you compare quotations for a panel built to this standard:
- Which standards does the panel carry on its rating plate?
- What voltage and temperature category are the capacitors rated for?
- What discharge arrangement is fitted, and how long does it take?
- Are the step fuses and contactors rated for the capacitor inrush and overcurrent?
- What tests are done at the factory, and will a record be issued?
A supplier who answers by listing brand names has not answered. The detail of the capacitors is in our LV power capacitors supply page.
What does the standard not decide for you?
A standard sets the minimum a design must meet. It does not size the bank or choose its type, and your project still has to settle these points:
- The kVAr. This comes from your demand and target power factor, as set out in PFC panel design and sizing.
- Plain or detuned. The harmonic content of your load decides it, and a survey measures it.
- Site conditions. Ambient temperature, dust and coastal humidity change the enclosure, cooling and capacitor temperature category.
- The tariff. The power factor target comes from your bill, not from the standard.
Two panels can both comply and still differ widely in cost and in service life, because the standard allows more than one design choice. Ask for the design basis, not only the compliance statement.
IEC 61921 APFC panel questions
Who provides an IEC 61921 APFC panel in Saudi Arabia?
Saudi Power Factor Company provides APFC panels in Saudi Arabia built in our Dammam workshops, designed to the standards on your specification and issued with a factory test record. State the standards you need when you request a quotation and we confirm each in the proposal.
Is IEC 61921 mandatory for an APFC panel?
It is mandatory when your specification, consultant or client says so, which is common on oil, gas and petrochemical projects. Otherwise it is the accepted benchmark for good design. Check the project specification, and where it is silent, ask your consultant which standards apply.
What affects the cost of a panel built to IEC 61921?
The factors are kVAr, steps, detuning reactors, enclosure rating, component brand and the testing and documents requested. Asking for extra type-test evidence or witnessed tests adds engineering time. Send your specification and the proposal separates each item.
How long does it take to build a panel to the standard?
The time depends on the kVAr, the reactor choice, drawing approval and the tests required. Our typical lead time is 2–3 weeks for an APFC panel and 3–4 weeks for a detuned bank. Prompt approval of drawings shortens the schedule more than any other single step on your side.
Does the standard replace IEC 61439?
The two work together. IEC 61439 governs the assembly and IEC 61921 governs the correction bank, so a project specification normally cites both. Ask your supplier for a statement showing which clauses of each are met.
Need an IEC 61921 APFC panel for your project? Send us your specification or one month of your electricity bill and receive a quotation within one working day.
Email: inquiry@saudipowerfactor.com | Request a quotation