A30046 — Power unit: Undervoltage alarm

The drive issues A30046, titled Power unit: Undervoltage alarm, when the voltage monitor in the internal FPGA of the PSA signals an undervoltage fault on the power unit. The timing matters: the manual states that the problem occurred before the last restart, so the message points to a supply problem from the time before the most recent power-up. Depending on the drive's configuration, the same condition can also be issued as a fault; in that form it must be acknowledged immediately by a POWER ON.

• A problem occurred at the power unit power supply before the last restart — the message reports a supply problem from the time before the most recent power-up.
• The undervoltage on the module was signaled by the voltage monitor in the internal FPGA of the PSA.

1. Check the 24 V DC voltage supply to the power unit.
2. Carry out a POWER ON for the component — switch it off and then on again.
3. If necessary, replace the module.

• The message value is the alarm value, which the drive stores in r2124; the manual says to interpret it as a decimal number.
• On the servo and vector drive objects, the alarm value is the register value of the voltage fault register.
• On the other drive objects listed for this code, the manual marks the alarm value as only for internal Siemens troubleshooting.

• r2124 (alarm value) — read the value stored here for this message, interpreted as a decimal, to obtain the register value of the voltage fault register on the drive objects where the manual decodes it.

As an alarm, A30046 needs no acknowledgement and triggers no automatic drive response. If the drive raises the same condition as a fault instead, the fault must be acknowledged immediately by a POWER ON — switch the power unit off and on again — once the 24 V DC supply has been checked. The remedy for the fault form is the same three steps: check the supply, carry out the POWER ON, and replace the module if necessary.