Resetting SINAMICS S120 Fan Alarm A30042 Operating Hours Counter

Resetting the SINAMICS S120 Fan Alarm A30042 Operating Hours Counter

Alarm A30042 "Fan has reached its maximum operating hours" is one of the most common service alarms encountered on SINAMICS S120/S150 power modules in continuous industrial service. The alarm is generated 500 hours before the factory-rated maximum operating time of the internal fan is reached and, by itself, does not stop the drive. However, if the counter is not reset after a fan replacement, the warning will reappear and may be followed by a fault that brings the drive down at the end of the remaining service interval. This reference covers the underlying alarm, the parameter set (p0251, p0252, p0253, p0254, p3961) used to manage fan service, the access-level and online prerequisites, and the field-proven reset procedure on the Drive Object expert list.

1. Problem Description

Operators observe the following symptoms on a SINAMICS S120 (for example, on a 6SL3120-2TE21-8AA3 single-axis Power Module in booksize format):

• The starter, SIMOTION Scout, TIA Portal, or SINAMICS Startdrive HMI displays A30042 on the affected drive object.
• The drive continues to run; the alarm is not a fault and does not trigger an OFF reaction.
• After physically replacing the fan, the alarm does not clear automatically.
• Attempts to find the reset parameters p0251 and p0254 in the standard parameter list, or in the Control Unit's expert list, fail — the parameters are simply not shown.
• When the operator navigates to the Service menu of the drive, a password prompt is displayed and the access-level indicator is grayed out.

This combination of symptoms almost always indicates that the operator is looking at the wrong device (the Control Unit) and at the wrong access level. The fan service parameters live on the Drive Object and require access level 3 to modify.

2. Root Cause Analysis

Per the official Siemens message documentation for A30042 ("Fan has reached its maximum operating hours"), the lifespan of the fans installed in SINAMICS power modules is limited by design. The drive continuously increments a wear counter that approximates the actual mechanical hours the fan has run. When that counter approaches the factory-defined end-of-life threshold, the drive issues A30042 as a pre-warning:

The A30042 warning "Fan has reached its maximum operating hours" is issued 500 hours before the factory-provided maximum operating time of the fan is reached.

This is intentionally a warning, not a fault. It is a maintenance signal. After the additional 500 hours of grace period, depending on the firmware version and configuration, the drive may then drop the alarm to a fault (typically F30042) and stop modulation on the affected axis. The two failure modes engineers observe in the field are:

1. Alarm only, drive runs — the most common state; the drive keeps running and the counter is reset only after the fan is replaced.
2. Fault F30042, drive stops — occurs when the 500-hour grace window elapses without operator intervention. This is what most field engineers eventually experience if they ignore the warning.

The reason the reset parameters cannot be seen is procedural, not electrical. The fan hour counters are owned by the power module / drive object, not by the Control Unit. The Control Unit (CU320-2, CU310-2, CU305) manages its own fans, which are counted by p3961. The motor-side / power-module-side fans are counted by p0251, p0252, p0253, p0254, and these are visible only when the expert list of the correct drive object is opened online with sufficient access rights.

3. Alarm, Fault, and Reaction

For detailed field reactions per firmware version, refer to the SINAMICS S120/S150 List Manual, function diagrams and fault/alarm chapters. The list manual is the authoritative source for the reaction setting of F30042 in any specific firmware release.

4. Parameter Reference — Fan Operating Hours

The fan-service parameter set is split between the Control Unit and the Drive Object. Knowing which is which is the single most important step in resolving the A30042 reset issue.

The values are of the type float / operating hours with one element per fan (where multiple fans are present on a power module). The "n" in the index represents the fan number, and p0252 sets the alarm threshold for the corresponding fan.

5. Prerequisites for the Reset

Before changing p0251 the following conditions must all be met. If any of them is not satisfied, the parameter will appear with a dotted (grayed) value and cannot be written.

1. Online connection — Connect the engineering tool (STARTER, SIMOTION Scout, TIA Portal, SINAMICS Startdrive, or use the BOP-20 / AOP30 operator panel) to the drive. Offline, all write-protected parameters display as dotted values and cannot be edited.
2. Drive Object selected, not Control Unit — In the project tree, expand the drive (e.g., "Drive_1"), then open the Expert list of the drive object. The Control Unit's expert list does not contain p0251 / p0254.
3. Access level ≥ 3 — The default level is "Standard" (level 1) or "Extended" (level 2). Switch to access level 3 (Service) before attempting to write p0251.
4. Parameter filters disabled — In STARTER/Scout, the expert list filter is sometimes set so that only a subset of parameters is shown. Clear all filters, or explicitly include p0251 / p0254 by index.
5. Write-protection (know-how protection) cleared — If the project is know-how protected, p0251 may be invisible or read-only. Remove the protection first.

6. Step-by-Step Reset Procedure (STARTER / SIMOTION Scout / TIA Portal)

The procedure is identical regardless of the engineering tool used; the screenshots and menu paths differ only cosmetically.

1. Open the project and go online with the SINAMICS S120 drive.
2. In the project tree, expand the drive (for example, Drive_1) and double-click Expert list on the Drive Object, not on the Control Unit.
3. Press Ctrl + F and type p0251 to locate the parameter directly. If it is not found, you are looking at the wrong device — switch to the drive object expert list.
4. Confirm the access level: right-click the parameter row → Access level → set to 3 (Service). Enter the service password when prompted.
5. Click the value cell of p0251. Enter 0 and press Enter. The parameter changes only when the drive is online; offline it remains dotted.
6. (Optional) Update p0254 to stamp the operating time of the new fan. Setting p0251 = 0 implicitly resets p0254 as well in many firmware versions, but the manual recommends verifying p0254 manually.
7. Press RAM to ROM (or Copy RAM to ROM) to make the change non-volatile. Without this step the reset is lost on the next power cycle.
8. Click the Acknowledge button to clear the pending alarm. A30042 is now gone.

7. Reset Procedure on BOP-20 / AOP30 Operator Panel

For cabinets without a PC, the reset can be performed directly on the optional operator panel:

1. Navigate the menu: MENU → SETUP → PARAMETER → ACCESS LEVEL and set access level to 3.
2. Return to the parameter menu and enter the parameter number r0251 / p0251.
3. Set p0251 = 0.
4. Press OK to write to RAM, then perform MENU → SETUP → SAVE RAM TO ROM to persist the change.
5. Acknowledge the alarm with the ACK key.

8. Reset Procedure on the Control Unit Fan (p3961)

If the affected fan is the CU internal fan (not the power module fan), use p3961 on the Control Unit expert list instead of p0251. The procedure is otherwise identical.

1. Go online with the CU and open the Control Unit expert list.
2. Set the access level to 3.
3. Set p3961 = 0 and confirm.
4. Save to ROM and acknowledge the alarm.

9. Fan Replacement Workflow

The recommended sequence — followed by all field engineers reporting success on the S120 — is:

1. Order the spare fan using the Siemens spares tool. Locate the correct order number by entering the SINAMICS part number (e.g., 6SL3120-2TE21-8AA3) at the official Siemens portal.
2. Wait for the spare to arrive before resetting p0251. Resetting p0251 before the swap causes A30042 to re-trigger immediately when the running fan continues to age, forcing a second reset right after the swap.
3. Power down the drive, replace the fan per the SINAMICS S120 equipment manual, and power the system back up.
4. Go online on the drive object expert list with access level 3.
5. Set p0251 = 0, optionally p0254 = 0, save to ROM, and acknowledge.
6. Verify the alarm is gone and p0251 is reading 0 (or near 0) hours.

10. Spare Parts Identification

For ordering, Siemens recommends the SOW (Spares on Web) tool:

1. Open the Siemens Spares on Web portal.
2. Enter the S120 order number (for example, 6SL3120-2TE21-8AA3).
3. From the resulting spare-parts list, select the matching fan assembly for the relevant power module.
4. Place the order and wait for delivery before resetting the counter.

11. Verification

After the reset, perform the following checks:

• Drive object expert list, parameter p0251 reads 0 (or the new fan's stamped hours).
• Parameter p0253 reads 0 (threshold signal cleared).
• Alarm buffer shows no A30042 entry after the reset.
• Fault buffer shows no F30042 entry.
• The fan is audibly running and the drive's intake temperature r0037[0] is within normal range.
• Power-cycle the drive to confirm the change is non-volatile (saved to ROM).

12. Troubleshooting Matrix

13. Preventive Maintenance Recommendations

• Schedule fan replacement before the A30042 alarm triggers — at approximately 80–90 % of the factory-set p0252 value — to avoid the drive-down scenario.
• Keep a spare fan in stock for each S120 power module on site. Spare fans are inexpensive relative to the cost of an unplanned line stop.
• Log p0251 values in the CMMS to track wear trend. A monotonically increasing p0251 across a fleet of identical drives is expected; deviations indicate either a fan replacement or a problem.
• Verify cabinet ambient temperature is within the SINAMICS S120 specification. Higher ambient temperature reduces fan life faster than the hours counter alone would suggest.
• Clean the fan inlet filters regularly. Clogged filters force the fan to run harder and shorten life.

14. Related Alarms and Faults

For an exhaustive list of all S120 messages and their reactions, refer to the SINAMICS S120/S150 List Manual, page 198 (and the alarm/fault appendix) for your specific firmware version.

15. Document References

• Siemens Support — A30042 "Fan has reached its maximum operating hours" (109480518)
• Siemens Support — SINAMICS S120/S150 List Manual (109763271)

FAQ