Siemens Capacitor: Complete Guide to SIECAP Capacitors, kVAR Ratings, Types, Applications & Selection

Power factor correction is an important part of modern industrial electrical systems. Motors, transformers, pumps, compressors, HVAC systems and other inductive loads consume reactive power, which can reduce system efficiency and increase the overall electrical demand. A properly selected power factor correction capacitor can help compensate for reactive power and improve the performance of an electrical installation.

Siemens capacitors, particularly the SIECAP range of cylindrical power capacitors, are designed for power factor correction applications in industrial and commercial electrical systems. At ElectriHub, Siemens capacitor options include different kVAR ratings, voltage ratings, duty classes and cylindrical capacitor configurations, making it easier for panel builders, electrical contractors and industrial users to select a capacitor according to their application.

ElectriHub's capacitor category includes Siemens along with other major capacitor brands, and its Siemens listings include SIECAP products such as Normal Duty and Heavy Duty cylindrical capacitors.

What Is a Siemens Capacitor?

A Siemens capacitor used for power factor correction is an electrical component designed to supply reactive power locally to inductive loads.

Industrial equipment such as:

• AC motors
• Pumps
• Compressors
• Transformers
• HVAC systems
• Welding equipment
• Industrial machinery
• Manufacturing equipment

can draw both active and reactive power from the electrical network.

Installing an appropriately rated power factor correction capacitor helps compensate for the reactive component of the load. Capacitors are commonly installed individually, in capacitor banks, or as stages in an Automatic Power Factor Correction (APFC) panel.

The Siemens SIECAP products listed by ElectriHub are cylindrical, three-phase power capacitors with different ratings depending on the model. For example, the 4RB2050-3EE53-8K is listed as a SIECAP Heavy Duty cylindrical three-phase capacitor rated at 5 kVAR, 415 V, while the 4RB2090-3EE52-8K is a Normal Duty version rated at 9 kVAR, 440 V.

Siemens SIECAP Capacitor Range Available at ElectriHub

The Siemens capacitor range on ElectriHub covers a broad selection of SIECAP cylindrical capacitors.

The major configurations represented in the ElectriHub listings include:

1. Siemens SIECAP Normal Duty Capacitors

Normal Duty Siemens capacitors are available for applications where the capacitor operates under comparatively standard electrical conditions.

Examples listed on ElectriHub include:

• 5 kVAR
• 6 kVAR
• 7 kVAR
• 7.5 kVAR
• 8.3 kVAR
• 9 kVAR
• 10 kVAR
• 11.1 kVAR
• 12.5 kVAR
• 13.8 kVAR
• 15 kVAR
• 16.7 kVAR
• 20 kVAR
• 20.8 kVAR
• 25 kVAR
• 27.7 kVAR
• 28 kVAR
• 30 kVAR

The exact kVAR availability varies by voltage and part number. ElectriHub's Siemens listings show Normal Duty versions at 415/440 V and 480 V, depending on the specific model.

1. Siemens SIECAP Heavy Duty Capacitors

For more demanding power factor correction applications, Siemens SIECAP Heavy Duty capacitors are also available through ElectriHub.

Examples of kVAR ratings represented in the product listings include:

• 5 kVAR
• 6.3 kVAR
• 7.5 kVAR
• 8.3 kVAR
• 10 kVAR
• 10.4 kVAR
• 11 kVAR
• 12.5 kVAR
• 13.2 kVAR
• 13.8 kVAR
• 15 kVAR
• 16.7 kVAR
• 20 kVAR
• 25 kVAR
• 26.5 kVAR
• 28.1 kVAR
• 30 kVAR
• 33.1 kVAR and other configurations

These ratings occur across different voltage configurations, including 415 V, 480 V and 525 V, depending on the Siemens part number.

For example, ElectriHub lists the 4RB2125-3EE53-8K as a 12.5 kVAR, 415 V Heavy Duty SIECAP capacitor, while the 4RB2300-3EE53-8K is listed as a 30 kVAR, 415 V Heavy Duty capacitor.

1. Siemens SIECAP Super Heavy Duty Capacitors

ElectriHub's Siemens listings also include SIECAP Super Heavy Duty cylindrical capacitors.

A representative listing is the 4RB1331-3FC50, identified as a 33.1 kVAR, 525 V, three-phase Super Heavy Duty cylindrical capacitor.

Super Heavy Duty capacitor configurations can be considered where the electrical installation requires a capacitor designed for more demanding operating conditions.

When selecting a Super Heavy Duty capacitor, however, engineers should evaluate the actual:

• Harmonic environment
• Voltage conditions
• Load profile
• Switching frequency
• Temperature
• Capacitor-bank configuration
• Detuning requirements

rather than selecting a higher-duty capacitor simply because it has a higher rating.

Siemens Capacitor kVAR Ratings Available at ElectriHub

One of the most important specifications when selecting a power factor correction capacitor is its kVAR rating.

The Siemens products indexed on ElectriHub cover numerous kVAR values.

Some of the ratings represented include:

These are examples of ratings found in ElectriHub's indexed Siemens capacitor listings, rather than a claim that every rating is currently in stock. Availability can change by product and configuration.

Siemens Capacitor Voltage Ratings

Selecting the correct rated voltage is just as important as selecting the correct kVAR rating.

The Siemens SIECAP products available through ElectriHub include different voltage configurations, such as:

415 V Siemens Capacitors

Commonly represented Heavy Duty configurations include:

• 5 kVAR
• 7.5 kVAR
• 10 kVAR
• 10.4 kVAR
• 12.5 kVAR
• 15 kVAR
• 20 kVAR
• 28.1 kVAR
• 30 kVAR

depending on the individual part number.

440 V Siemens Capacitors

ElectriHub also lists Normal Duty SIECAP capacitors such as:

• 5 kVAR
• 6 kVAR
• 7 kVAR
• 7.5 kVAR
• 8.3 kVAR
• 9 kVAR
• 10 kVAR
• 11.1 kVAR
• 12.5 kVAR
• 15 kVAR
• 16.7 kVAR
• 20 kVAR
• 20.8 kVAR
• 28 kVAR
• 30 kVAR

according to the indexed product configurations.

480 V Siemens Capacitors

The ElectriHub range also contains Siemens SIECAP configurations at 480 V, including Normal Duty and Heavy Duty options.

Examples include:

• 5 kVAR
• 8.3 kVAR
• 10.4 kVAR
• 11 kVAR
• 12.5 kVAR
• 13.8 kVAR
• 15 kVAR
• 16.7 kVAR
• 20 kVAR
• 20.8 kVAR
• 25 kVAR
• 27.7 kVAR
• 28.1 kVAR
• 30 kVAR

depending on the specific part number.

525 V Siemens Capacitors

Higher-voltage configurations are also represented, particularly in Heavy Duty and Super Heavy Duty products.

Examples include:

• 5 kVAR
• 6.3 kVAR
• 8.3 kVAR
• 10.4 kVAR
• 12.5 kVAR
• 13.2 kVAR
• 15 kVAR
• 25 kVAR
• 26.5 kVAR
• 33.1 kVAR

The specific voltage and kVAR combination must always be confirmed against the individual Siemens part number.

Siemens Capacitor Series and Part Number Structure

When searching for Siemens capacitors online, users will frequently encounter part numbers beginning with 4RB.

Examples from the ElectriHub catalogue include:

• 4RB2050-3EE52-8K
• 4RB2050-3EE53-8K
• 4RB2050-3EJ52-8K
• 4RB2075-3EE52-8K
• 4RB2083-3EE52-8K
• 4RB2090-3EE52-8K
• 4RB2100-3EE53-8K
• 4RB2125-3EE53-8K
• 4RB2150-3EE53-8K
• 4RB2200-3EE52-8K
• 4RB2208-3EE52-8K
• 4RB2250-3EJ52-8K
• 4RB2281-3EE53-8K
• 4RB2300-3EE53-8K
• 4RB1331-3FC50

These part numbers correspond to different combinations of kVAR rating, voltage, duty class and electrical configuration.

Because the suffix can change the voltage, duty category or other specification, it is important not to select a Siemens capacitor only by the first part of the model number.

How Does a Siemens Power Factor Correction Capacitor Work?

Inductive loads such as motors require reactive power to establish their magnetic fields. This reactive power increases the current flowing through the electrical system without directly contributing to useful mechanical output.

A capacitor supplies capacitive reactive power that offsets part of the inductive reactive demand.

In simple terms:

Inductive load → consumes reactive power

Capacitor → supplies reactive power

Result → improved power factor

A better power factor can help reduce unnecessary current flow and improve the utilization of electrical infrastructure.

In an APFC panel, multiple Siemens capacitor stages can be automatically switched according to the reactive power requirement of the load.

Why Is kVAR Important in Siemens Capacitor Selection?

kVAR, or kilovolt-ampere reactive, represents the reactive power rating of a capacitor.

Choosing the right kVAR rating is critical.

For example:

• A 5 kVAR capacitor provides a relatively small amount of reactive power compensation.
• A 10 kVAR capacitor provides approximately twice the reactive compensation of a 5 kVAR unit under comparable rated conditions.
• A 25 kVAR capacitor can provide significantly greater compensation for larger industrial loads.
• A 30 kVAR capacitor may be suitable for larger capacitor-bank stages where the electrical system requires higher reactive compensation.

However, the required capacitor size should be calculated from the actual load and desired power factor rather than selected only according to motor horsepower or transformer size.

How to Calculate Required Capacitor kVAR?

A commonly used power factor correction formula is:

Qc = P × (tan φ₁ − tan φ₂)

Where:

• Qc = required capacitor rating in kVAR
• P = active power in kW
• φ₁ = angle corresponding to the existing power factor
• φ₂ = angle corresponding to the desired power factor

For example, if an industrial installation has a significant inductive load and its existing power factor is low, the required capacitor bank can be calculated based on the present and target power factors.

For an APFC system, the total capacitor-bank capacity is normally divided into multiple stages instead of using a single large capacitor.

Siemens Capacitor Applications

Siemens SIECAP capacitors can be used in a wide range of electrical applications, including:

Industrial Plants

Manufacturing facilities often have large numbers of motors and inductive machines. Power factor correction capacitors can help compensate for the reactive demand.

Motor Control Panels

Capacitors can be incorporated into electrical systems supplying motors and other inductive equipment.

APFC Panels

Multiple Siemens capacitor stages can be used with an APFC relay to automatically maintain the required power factor.

HVAC Systems

Large HVAC installations contain motors, compressors and other inductive equipment that can require reactive power compensation.

Pumping Stations

Industrial and commercial pumping systems can use power factor correction to improve electrical system efficiency.

Commercial Buildings

Large buildings with elevators, HVAC systems, pumps and other motor-driven equipment can benefit from appropriate power factor correction.

Transformer and Distribution Systems

Capacitors can be used as part of a broader power-quality and reactive-power management strategy.

Normal Duty vs Heavy Duty vs Super Heavy Duty Siemens Capacitors

Choosing between duty classes is an important part of capacitor selection.

The correct choice depends on the actual electrical environment rather than simply choosing the highest-duty product.

If the installation contains significant harmonic-producing equipment such as VFDs, UPS systems, rectifiers or variable-speed drives, harmonic analysis should be performed before installing capacitor banks.

A detuned reactor may be required in harmonic-rich installations to reduce the risk of resonance and capacitor stress.

Siemens Capacitor Selection Guide

Before selecting a Siemens capacitor, check the following specifications:

1. kVAR Rating

Determine the required reactive power compensation.

1. Rated Voltage

Match the capacitor's rated voltage to the electrical system and capacitor-bank design.

1. Duty Class

Choose between Normal Duty, Heavy Duty or Super Heavy Duty based on the application.

1. Phase

The Siemens SIECAP products discussed here are three-phase cylindrical capacitors.

1. Frequency

Verify compatibility with the system frequency.

1. Harmonics

Check whether VFDs, UPS systems, rectifiers or other nonlinear loads are present.

1. Capacitor Switching

For APFC applications, consider the switching frequency and required stage sizes.

1. Installation Environment

Temperature, ventilation, enclosure design and ambient conditions can influence capacitor life and performance.

1. Part Number

Always match the complete Siemens part number rather than selecting a product based only on kVAR.

Siemens Capacitor for APFC Panels

An Automatic Power Factor Correction panel typically consists of:

• APFC relay
• Capacitor contactors
• Power factor correction capacitors
• HRC fuses or protective devices
• Busbars
• Detuned reactors where required
• Current transformer
• Control wiring

The APFC relay monitors the power factor and switches capacitor stages according to the reactive power requirement.

For example, a panel may use several capacitor stages rather than one large capacitor:

5 + 5 + 10 + 10 + 20 kVAR = 50 kVAR

This staged configuration allows the APFC system to respond more accurately to changing loads.

Siemens Capacitor vs Standard Capacitor: What Should You Consider?

When selecting a power factor correction capacitor, brand alone should not be the only consideration.

Compare:

• kVAR rating
• Rated voltage
• Duty category
• Capacitor technology
• Harmonic compatibility
• Temperature rating
• Expected operating conditions
• Service life
• Physical dimensions
• Mounting arrangement
• Availability of the exact replacement part

Siemens SIECAP products available on ElectriHub provide multiple combinations of these specifications, allowing electrical professionals to select a product according to the requirements of their installation.

Siemens Capacitor Price and Availability

The price of a Siemens capacitor depends on its kVAR rating, voltage, duty class, configuration and specific part number.

For example, ElectriHub currently lists individual SIECAP products such as the 4RB2050-3EE53-8K 5 kVAR Heavy Duty 415 V capacitor and the 4RB2300-3EE53-8K 30 kVAR Heavy Duty 415 V capacitor. Product availability and pricing can vary by model and can change over time.

For project requirements, OEM panels, replacement requirements and bulk quantities, it is recommended to verify the exact Siemens part number and current availability before ordering.

Why Choose ElectriHub for Siemens Capacitors?

ElectriHub provides an online platform for sourcing electrical, switchgear, automation and power-quality products.

The capacitor category includes major brands such as Siemens, Schneider Electric, L&T and Epcos/TDK, along with a wide selection of kVAR ratings.

When sourcing Siemens capacitors through ElectriHub, customers can:

• Search by Siemens part number
• Compare capacitor specifications
• Check kVAR ratings
• Review voltage ratings
• Identify Normal Duty and Heavy Duty options
• Request project or bulk quantities
• Check product availability
• Submit enquiries for specific requirements

ElectriHub also supports enquiry-based procurement for project requirements and bulk quantities.

Explore Siemens Capacitors at ElectriHub

If you are looking for a Siemens capacitor for power factor correction, APFC panels, industrial electrical systems or capacitor-bank applications, explore the Siemens SIECAP range available through ElectriHub.

Frequently Asked Questions About Siemens Capacitors

What is a Siemens capacitor used for?

Siemens power capacitors are commonly used for power factor correction and reactive power compensation in industrial and commercial electrical systems.

Which Siemens capacitor kVAR ratings are available?

ElectriHub's indexed Siemens range includes ratings such as 5, 6, 6.3, 7, 7.5, 8.3, 9, 10, 10.4, 11, 11.1, 12.5, 13.2, 13.8, 15, 16.7, 20, 20.8, 25, 26.5, 27.7, 28, 28.1, 30 and 33.1 kVAR, among other configurations. The exact rating depends on the Siemens model and voltage.

Are Siemens capacitors available in 415 V?

Yes. ElectriHub lists multiple Siemens SIECAP Heavy Duty configurations at 415 V, including 5, 7.5, 10, 10.4, 12.5, 15, 20, 28.1 and 30 kVAR examples.

Are Siemens capacitors available in 440 V?

Yes. ElectriHub lists Siemens Normal Duty SIECAP capacitors in several kVAR ratings at 440 V, including 5, 6, 7, 7.5, 8.3, 9, 10, 11.1, 12.5, 15, 16.7, 20, 20.8, 28 and 30 kVAR examples.

What is the difference between Normal Duty and Heavy Duty capacitors?

The duty category indicates the intended operating conditions and design requirements of the capacitor. Heavy Duty capacitors are generally selected for more demanding applications, but the correct choice should be based on the actual system conditions.

Can Siemens capacitors be used in APFC panels?

Yes. Siemens power capacitors can be used as stages within an APFC system, provided the capacitor specifications, switching arrangement, protection and harmonic conditions are appropriately designed.

How do I choose the correct Siemens capacitor?

Start with the required kVAR, system voltage, phase, frequency, duty class and harmonic conditions. Then select the exact Siemens part number matching those requirements.

Final Thoughts

Choosing the right Siemens capacitor is more than selecting a kVAR value. The correct capacitor must match the electrical system's voltage, reactive power requirement, operating conditions, duty class and harmonic environment.

The Siemens SIECAP capacitor range available through ElectriHub includes Normal Duty, Heavy Duty and Super Heavy Duty cylindrical configurations across a broad selection of kVAR and voltage ratings. This makes the range suitable for applications ranging from standard power factor correction to more demanding industrial installations.

For the best result, always select the capacitor using the complete Siemens part number and technical specifications, not just the kVAR rating.

Looking for Siemens capacitors online? Explore the available Siemens SIECAP range at ElectriHub and select the required kVAR, voltage and duty configuration for your application.