Define the Safety Calculation Boundary
The application is a VSD outgoing feeder whose final switching element is a Siemens 3WL air circuit breaker (ACB), part number 3WL1208-4CB38-1AA2. The stated target is Performance Level PL d, Category 3. The available evidence does not establish that this target is achieved; it only defines the required result.
The Safety Evaluation Tool (SET) does not provide an ACB choice in the reaction section. The existing calculation uses a 3RT power contactor, while the intended reaction element is the 3WL ACB. Treat the ACB as a separately entered component rather than retaining the contactor data.
Use the Supported SET Entry Method
| Element | Available evidence | SET treatment |
|---|---|---|
| 3SK1 safety relay | Safety parameters are identified in Section 13, Technical Data, of the 3SK1 safety-relay manual. | Use the values applicable to the selected 3SK1 device. |
| 3WL ACB | Safety values are available for the 3WL family, but no numerical value is included in the supplied evidence. | Select Third-party manufacturer and the option to calculate the failure rate with a B10d value. |
| Existing 3RT contactor | Used in the reference SET calculation. | Replace it with the 3WL entry only if the remaining setup is identical. |
The third-party entry is a SET data-entry method; it does not change the actual manufacturer of the ACB. Do not copy the 3RT contactor's safety value into the 3WL entry.
Configure the 3WL Reaction Element
- Confirm that the installed ACB is
3WL1208-4CB38-1AA2. - Obtain the applicable
B10orB10dvalue from the 3WL documentation or Siemens Online Support. Do not enter a guessed value because the evidence supplies no numerical value for this part number. - Open the reaction section of the existing SET project and replace the 3RT contactor with
Third-party manufacturer. - Select the failure-rate calculation method based on a
B10dvalue and enter the documented 3WL data together with the operating assumptions required by SET. - Use the applicable 3SK1 safety parameters from Section 13 of its manual for the safety-relay portion of the calculation.
- Recalculate the safety function and compare the reported result with the required
PL d, Category3.
Verify the Result and Service-Life Constraint
Confirm that replacing the 3RT with the 3WL has not changed any other part of the modeled safety function. If the architectures differ, rebuild the calculation around the actual circuit rather than treating the devices as interchangeable.
The 3WL safety information referenced in the evidence includes a maximum service-life consideration of 20 years. Verify the exact applicability and conditions in the documentation used for the selected breaker. Archive the 3WL source value, 3SK1 technical data, SET report, device part numbers, and operating assumptions with the safety validation record.
FAQ
How do I add a 3WL ACB to the Safety Evaluation Tool?
Select Third-party manufacturer in the reaction section, choose the failure-rate calculation method using a B10d value, and enter the documented data for the 3WL breaker.
Can I use the 3RT contactor data for a 3WL1208-4CB38-1AA2?
No. Replace the 3RT entry with the 3WL's documented B10 or B10d data, and make the substitution only when the rest of the SET setup remains identical.
Does entering the 3WL B10d value prove PL d Category 3?
No. It supplies data for the reaction element; SET must recalculate the complete safety function, and the resulting report must meet the stated PL d, Category 3 requirement.