SIEMENS SITOP Power SupplyHow to选：24V 配电的型号、电流和常见坑
Published：2026-08-25 · Brand：西门子 · Category：选型指南
Woke up in the middle of the night by a live phone call saying that the device had been randomly restarted. I rushed over to check the night, and finally found that the 24V power supply did not move - the module's operating current was up to protection, the voltage dropped, and the PLC restarted. In nine out of ten such accidents, the power supply was small, not the power supply was broken.
SITOP is Siemens' switching power supply, which is much more common in cabinets. Select it is not complicated: first set the series, then calculate the current, and finally see if you want accessories. PSU100M is economical, 24V output, short circuit, overload protection, most cabinets use it enough. 6EP1332-4BA00 is 24V/5A, 120W, with a set of S7-1200 plus more than enough sensors. The PSU8600 with diagnostic communication, wide range voltage regulation, the price difference is several times, not all occasions need.
The current is counted towards the wide mile. The PLC backplane current, sensor, solenoid valve, indicator light, touch screen, all add up and multiply by 1.2 to 1.5. Do not match the manual with the nominal full load - it is common to add a valve and a lamp on site, and the power reserve is more real than anything else. I have seen that the customer is just right according to the nominal calculation. After two months on the line, the equipment is added. The power supply can't hold and it is large, so it tosss and tosses back and forth.
Attachments are not fully equipped. If the power failure requires storing data for a few seconds, add a buffer module; if the two power supplies are parallel to improve reliability, add a redundant module; if you want to know the power failure remotely, select the model with diagnosis. Ordinary production lines are not suitable first, wait for demand to increase, don't spend the budget of the cabinet at once.
Let's talk about the two site pits. The 24V negative electrode is not randomly grounded, and it will be handled uniformly according to the system requirements, otherwise the interference will not be checked; the power supply cabinet is far away from the heat source, and the SITOP full-load operating temperature is not low, and the heat dissipation will not be protected in advance.
Selection Comparison Table
| 场景 | 推荐 | Description |
|---|---|---|
| Standard cabinet 24V power supply | PSU100M 24V/5A（6EP1332-4BA00） | 120W, economical, enough PLC + sensor |
| Heavy load | PSU100M 24V/10A | 240W, allowance |
| Outage protection | PSU100M + Buffer Module | Power off Holds data for a few seconds |
| Highly reliable two-way | PSU100M × 2 + redundant module | Parallel power supply, all the way hung up without stopping |
Note: Specifications are based on manufacturer public data and may vary by batch. Please verify with current OEM documentation.
FAQ
Q：How is the SITOP power supply current calculated?
A：All 24V load currents are added (including PLC backplane, sensors, actuators, and indicator lights), leaving a margin of 20% ~ 50%.
Q：What is the difference between PSU100M and PSU8600?
A：The PSU100M is economical, basic protection; the PSU8600 supports PROFINET diagnostics, wide range voltage regulation, programmable, and the price is one order of magnitude higher.
Q：Need a buffer module?
A：When the power grid is unstable or power is cut off, data/normal shutdown should be stored; ordinary production lines can not be matched, and the main power current margin should be guaranteed first.
Related Models & Brands
› 6EP1332-4BA00 Model Details › Brand Page