Siemens Introduces UL-Certified Variants to the Sentron 3WA Circuit Breaker Family
Siemens announces the release of model extensions to the Sentron 3WA series of low-voltage air circuit breakers certified to UL standards.
Based on an air circuit breaker (ACB) design, Siemens has released two UL-certified versions of its 3WA power circuit breaker series: 3WA2 and 3WA3.
Siemens 3WA circuit breaker series. Image used courtesy of Siemens
The 3WA2 is designed specifically for the UL 489 market, while the 3WA3 accommodates UL 1066 and IEC 60947-2 standards, allowing for global use by customers. The two models complement the 3WA1 model released in the fall of 2020 for IEC markets.
The Sentron 3WA series of air circuit breakers are designed for low-voltage AC and DC switchboards and are available in three frame sizes with current ratings from 630 to 6300 A.
3WA Air Circuit Breaker
The main function of ACBs in low-voltage switchboards is to protect electrical installations in buildings, infrastructure, and industrial facilities from damage to equipment shorts or overload conditions. They are also useful for protecting critical infrastructure in hospitals and data centers and for electric motor protection.
Configuring the 3WA trip unit via USB or Bluetooth. Image used courtesy of Siemens
The 3WA can be used as a circuit breaker with an electronic trip unit or as a non-automatic circuit breaker per IEC 60947-2. The electronic trip unit is controlled by an internal microprocessor (MCU). It can be configured using the SENTRON power config configuration software running on a laptop via USB or Bluetooth. A separate MCU is used for metering and accessory functionality.
The 3WA series is rated based on model size, with the highest rated size handling up to 6300 A of current with a breaking capacity of 125 kA at 1000 V AC. The breaker is suitable for use in both AC and DC applications.
The breaker can be installed in a fixed-mounted or withdrawable configuration, and the compact form factor of the breaker allows it to fit within a 1-meter-wide control panel.
Using the 3WA to protect IE3 and IE4 motors. Image used courtesy of Siemens
Three frame sizes for the 3WA breaker series. Image used courtesy of Siemens
Certifying to Global Standards
Certifying an existing platform, like the 3WA, to new standards is common for manufacturers who want to sell their products in global markets governed by different equipment or system requirements (North America, Europe, etc.).
In many cases, the new certification will require few, if any, design changes but can involve extensive system testing and certification to the new requirements. Any design changes, or modifications to production testing and verification, will warrant release under a new model number, as is the case for the 3WA2 and 3WA3.
While easier in certain respects, having a single model or variant certified to all global standards may not be cost-effective.
UL 489 and UL 1066 Standards
UL is an accredited standards developer in the US and Canada with over 100 years of development experience across 1500 standards.
The UL 489 standard covers key specifications for molded-case circuit breakers, other circuit breakers, ground-fault circuit interrupters, and similar protective devices. The circuit breakers covered by the standard include the 3WA designed to provide service entrance, feeder, and branch circuit protection per the National Installation Codes. The standard covers devices rated at 1000 V AC and 1500 V DC or less and up to 6000 A.
UL 1066 applies to low-voltage AC power circuit breakers up to 1058 V and encompasses stationary and draw-out-mounted types, multi-pole construction, and manually or power-operated trip devices.
