Protective circuits
Desktop power supply units (PSUs) have several protective functions to protect both the PSU itself and the connected PC components such as the mainboard, CPU, GPU and drives. These protection mechanisms prevent damage caused by electrical faults, overloads or unusual operating conditions. I tested the protection functions of the power supply at the default settings without connecting it to a system. The 12 V rail is conservatively set, but a greater difference between standard and high operating temperature would be desirable. The secondary rails have very high OCP trip values, and even more problematic is that the OCP value is even higher at 5 V under high temperatures, while at 3.3 V it remains almost unchanged. Since the power supply unit is subjected to higher loads at high temperatures, the OCP trip values should actually fall in this case.
The trigger values of the overload protection function (OPP) are also not set correctly, as they remain identical at standard and high temperatures. Nevertheless, they are set rather conservatively overall. All other important protective functions are present and work perfectly, and the platform also has fan failure protection. If the fan is not connected or is not working properly, the power supply switches off automatically after a short time.
| OCP (Normal @ 27.6°C) | 12V: 102.00A (122.45%), 11.989V 5V: 35A (140.00%), 5.069V 3.3V: 34.6A (138.40%), 3.365V 5VSB: 4.7A (134.29%), 5.079V |
| OCP (Hot @ 45.3°C) | 12V: 103.20A (123.89%), 11.985V 5V: 35.3A (141.20%), 5.064V 3.3V: 34.6A (138.40%), 3.361V 5VSB: 4.6A (131.43%), 5.069V |
| OPP (Normal @ 27.6°C) | 1209.03W (120.90%) |
| OPP (Hot @ 43.3°C) | 1209.06W (120.91%) |
| OTP | ✓ (106°C @ Secondary Side) |
| SCP | 12V to Earth: ✓ 5V to Earth: ✓ 3.3V to Earth: ✓ 5VSB to Earth: ✓ -12V to Earth: ✓ |
| PWR_OK | Proper Operation |
| NLO | ✓ |
| Fan Failure Protection | ✓ |
| SIP | Surge: MOV Inrush: NTC & Bypass Relay |
EMC pre-testing at a glance
Any electronic device, including power supplies, can be a source of electromagnetic interference (EMI), and the amount of EMI emitted can affect the proper operation of surrounding devices. In extreme cases, EMI can even render them unusable. Appropriate standards have been defined to limit electromagnetic interference. For IT products, the standards CISPR 32 and the EN 55032 derived from it apply, which is binding for products in the EU. In the EU, every product with CE marking must meet the requirements of EN 55032. CISPR 32 and EN 55032 divide devices into two classes: A and B. Class B devices are intended for use in a domestic environment and may therefore have significantly lower interference emissions than Class A devices.
Measuring equipment used to record EMI emissions:
– TBMR-110M EMI analyzer (DC-110 MHz)
– Tekbox TBLC08 LISN
– Tekbox TBFL1 transient limiter
– Tekbox Software
| CISPR 32 / EN55032 Limits | ||
| CISRP 32 / EN 55032 Class A Conducted EMI Limit | ||
| Frequency of Emission (MHz) | Conducted Limit (dBuV) | |
| Quasi-peak | Average | |
| 0.15 – 0.50 | 79 | 66 |
| 0.50 – 30.0 | 73 | 60 |
| CISPR 32 / EN 55032 Class B Conducted EMI Limit | ||
| Frequency of Emission (MHz) | Conducted Limit (dBuV) | |
| Quasi-peak | Average | |
| 0.15 – 0.50 | 66 – 56 | 56 – 46 |
| 0.50 – 5.00 | 56 | 46 |
| 5.00 – 30.00 | 60 | 50 |
| CISRP 32 / EN 55032 Class A 10-Meter Radiated EMI Limit | ||
| Frequency of Emission (MHz) | Field Strength Limit (dBuV/m) | |
| 30 – 88 | 39 | |
| 88 – 216 | 43.5 | |
| 216 – 960 | 46.5 | |
| > 960 | 49.5 | |
| CISRP 32 / EN 55032 Class B 3-Meter Radiated EMI Limit | ||
| Frequency of Emission (MHz) | Field Strength Limit (dBuV/m) | |
| 30 – 88 | 40 | |
| 88 – 216 | 43.5 | |
| 216 – 960 | 46.0 | |
| > 960 | 54.0 | |
It should be noted that the ATX specification allows a tolerance of 4 dB for conducted and radiated emissions. This means that a power supply that exceeds the limits but remains within this 4 dB tolerance still meets the corresponding requirements of the ATX specification (section 8.1 Emissions).
EMI results: The electromagnetic emissions of the power supply are well under control.
On the next page we will now go inside, please turn the page!
- 1 - Introduction, Prices and Technical Data
- 2 - Unboxing, Cables and iCUE
- 3 - Protection and EMI
- 4 - Teardown: Topology, components and craftmanship
- 5 - Load Regulation, Ripple Suppression, Transient Resonse
- 6 - Hold-Up Time, Timings, Inrush-Current
- 7 - Average Efficiency and PF
- 8 - Operating noise and fan
- 9 - Summary and conclusion
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