Power terminal protection scheme based on Semiconductor discharge tube (TSS) devices
AC Power port - Reasons for Lightning Protection Design (I)
Asked to do 480 vac UL62368-1 withstand voltage test
DECEMBER 1, 2014 CAN/CSA C22.2 NO.62368-1-14·UL62368-1 115
| AC mains voltage aup to and including |
Mains transient voltage b V peak |
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|---|---|---|---|---|
| V r.m.s. | Overvoltage category | |||
| I | II | III | IV | |
| 50 | 330 | 500 | 800 | 1500 |
| 100c | 500 | 800 | 1500 | 2500 |
| 150d | 800 | 1500 | 2500 | 4000 |
| 300e | 1500 | 2500 | 4000 | 6000 |
| 600f | 2500 | 4000 | 6000 | 8000 |
| a For equipment designed to be connected to a three-phase 3-wire supply,where there is no neutral conductor,the a.c. MAINS supply voltage is the line-to-line voltage.Inall other cases,where there is a neutral conductor,it is the line-to- neutral voltage. b The MAINS TRANSIENT VOLTAGE is always one of the values in the table.Interpolation is not permitted. CIn Japan,the value of the MAINS TRANSIENT VOLTAGES for the nominal a.c.MAINS supply voltage of 100 V is determined from columns applicable to the nominal a.c.MAINS supply voltage of 150 V. dIncluding 120/208 V and 120/240 V. e Including 230/400 V and 277/480 V. fInduding 400/690V. |
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AC Power port - Reasons for Lightning Protection Design (II)
IEC62368 overload test requirements: overvoltage tests > 2 * vr (vr = 220 vac)
IEC62368 Chapter G.8--- 8.3.2 Overload test
The following test is simulated as required by Table G.7 to either a varistor or a surge suppression circuit containing varistors connected across the mains (L to L or L to N), line to protective earth (L to PE), or neutral to protective earth (N to PE).
Table G.7 – Varistor overload and temporary overvoltage test
| Maximum continuous a.c. voltage of a varistor | Connection Between | ||
| L to N or L to L | L to PE | N to PE | |
| 1.25 × Vr to 2 × Vr | G.8.3.2 | G.8.3.2 and G.8.3.3 | G.8.3.2 and G.8.3.3 |
| Over 2 × Vr to 1200 + 1.1 × Vr | No test | G.8.3.3 | G.8.3.3 |
| Over 1200 + 1.1 × Vr | No test | No test | No test |
| Vr is the rated voltage or the upper voltage of the rated voltage range of the equipment. | |||
The following test simulation circuit shall be used:
- Voltage is the AC source of 2 × Vr.
- Current is the current resulted from a test resistor Rx connected in series with the AC source.
- Vr is the rated voltage or the upper voltage of the rated voltage range of the equipment.
Example： If 220VAC(rms) equipment and need to pass 4kV/2kA(level2, G8.2 table13), OVP device will be chose at >440VAC rms.
AC power port - Differences between traditional lightning protection and PROSEMI's innovative lightning protection
Differential mode lightning protection：MOV+GDT
Differential mode lightning protection：MOV+TSS complexCombined device
Innovative Highlights of the PROSEMI Solution
Integrated design: Miniaturization, surface mount technology, low-cost multi-functionality, and a trend towards greater safety. This is the requirement of automated production and also the need for products to be safer
Comparison of Turn-off Mechanisms Between TSS and GDT
Principle: Both TSS and GDT are switch-type devices, but their turn-off mechanisms are different. TSS is turned off by current, and GDT is turned off by voltage.
After the GDT is broken down and conducts, the applied voltage will be directly applied across the MOV terminals. Only when the AC voltage crosses the zero point can it be turned off.
After the TSS is broken down and conducted, the TSS is immediately turned off when the surge current is less than the holding current (IH).
Performance Analysis of AC Power Port - Lightning Protection Scheme
| Item | Traditional Lightning Protection Solution | PROSEMI Improved Lightning Protection Solution |
|---|---|---|
| L, N Line Device Matching |  |
 = |
| Performance Analysis | 1. Large breakdown voltage tolerance in GDT (±20%~±30%), requiring ample design margin. 2. Slow response time of GDT (≤100ns); due to surge waveform dv/dt, resulting in higher clamping voltage. 3. GDT + MOV pairing helps reduce MOV leakage current, extending MOV lifespan. 4. Large footprint, not ideal for compact designs. | 1. Lower clamping voltage: TSS offers significantly faster response time and tighter voltage tolerance than GDT, resulting in lower clamping voltage. 2. Low leakage current: The TSS + MOV combination increases the cycle count before MOV leakage rises to 4.5μA by 4.3× compared to single MOV, and 1.4× compared to GDT + MOV. 3. High reliability: The number of test cycles before MOV aging in TSS + MOV is 4.4× that of a single MOV, and 1.5× that of GDT + MOV. TSS significantly extends MOV lifespan. 4. Compact size: Integrated design saves at least 50% space compared to discrete MOV + GDT configurations. |
Lightning protection design is closely related to circuit protection; both aim to ensure the safe operation of electrical equipment through various protective measures, even when subjected to power fluctuations and lightning strikes. There are many differences between traditional and innovative lightning protection technologies, especially in the application of AC power outlets. How to select appropriate lightning protection solutions based on different environments and requirements is a topic that requires in-depth discussion. This article will provide a detailed analysis of the differences between traditional and innovative lightning protection technologies for AC power outlets, helping readers better understand the characteristics, advantages, and applicable scenarios of these technologies.