MDAY 34S132K MOV 1000h DC Aging Test Report: Long-Term Stability & Competitor Comparison
MDAY 34S132K MOV 1000h DC Aging Test Report: Long-Term Stability & Competitor Comparison
Executive Summary
The MDAY 34S132K Metal Oxide Varistor (MOV) completed 997 h effective DC aging at 115 °C / DC 1140 V (≡ Uc) per Clause 8 of GB/T 18802.331-2024. All three samples passed: ΔU1mA +1.4% to +2.8% (within ±10%), standby leakage 2.6–3.1 μA (≤50 μA), α 35–38 (≥25), online leakage steadily stable with no thermal runaway, and structure intact. In the same-spec comparison, the competitor “34S132K” suffered thermal runaway at ~32 h and failed.
1. Overview
This test is conducted in accordance with Clause 8 “Reliability / Endurance (aging) test” of GB/T 18802.331-2024, applying a 1000 h DC constant-voltage high-temperature aging to MDAY 34S132K MOV, to verify its long-term stability and life margin under maximum continuous operating voltage and maximum operating temperature.
Three same-batch samples (internal code: Leters 34S132K; U1mA = 1371–1375 V by 1 mA method) were aged in a 115 °C oven under DC 1140 V (= 0.83 × U1mA, DC Uc level), with leakage current and power of three channels monitored in real time.
| Item | Description |
|---|---|
| Samples | MDAY 34S132K (internal code: Leters), 3 pcs, Φ34 mm disc, nominal V1mA = 1320 V (K class ±10%) |
| Tester / Date | Wei Liyong / from 2026-08-20 |
| Aging temp. | 115 °C (constant oven, uniform circulation, fluctuation ≤ ±5 °C) |
| Applied voltage | DC constant 1140 V (= 0.83 × U1mA, DC Uc level) |
| Effective aging | 997 h (meets the 1000 h endurance requirement) |
| Interruptions | Power upgrade 116 h + typhoon “White Dolphin” 160 h; 276 h total power-off, ~1273 h elapsed |
| Online monitoring | 3 channels (I1, I2, I3) leakage & power, 262 data points |
| Online result | Leakage relaxed from 134 / 118 / 124 μA to steady 48 / 40 / 43 μA; no thermal runaway |
2. Test Basis
- GB/T 18802.331-2024 “Low-voltage surge protective devices components — Part 331: Performance requirements and test methods for MOV” (effective 2024-09-01, mod. adopts IEC 61643-331:2020, replaces GB/T 18802.331-2007) — primary basis.
- GB/T 18802.1-2011 “Low-voltage SPD — Part 1: Performance requirements and test methods” and GB/T 18802.11.
- IEC 61051-2 “Varistors for use in electronic equipment — Part 2: Sectional specification for surge suppression varistors” (reference for leakage current and non-linear coefficient).
Clause 8 endurance test requires MOV to be stressed at Uc (maximum continuous operating voltage) at maximum operating temperature for 1000 h; after returning to room temperature, the measured varistor voltage Uv and leakage Idc shall change within ±10% to pass. This test runs at 115 °C + DC Uc-level voltage for 997 h effective aging, satisfying the 1000 h requirement; power-off interruptions are idle 搁置 and excluded from aging stress.
3. Conditions & Method
| Parameter | Condition |
|---|---|
| Aging temp. | 115 °C (constant, uniform circulation, fluctuation ≤ ±5 °C) |
| Applied voltage | DC constant 1140 V (= 0.82–0.85 × U1mA, i.e. DC Uc level) |
| Monitored | Real-time leakage I (μA) and power P (mW) = U × I per channel |
| Pre/Post 3-param | U1mA (1 mA method), IL (0.75U1mA) standby leakage, α non-linear coefficient |
| Pre-action | After aging, cool 1~2 h, then re-measure 3-param at room temperature |
4. Acceptance Criteria
Per Clause 3 “Failure definition” and Clause 8 endurance of GB/T 18802.331-2024, a single MOV passes only if ALL of the following are met; failure of any one rejects the part:
| # | Item | Pass requirement | Basis |
|---|---|---|---|
| 1 | Structural damage | No crack/performance, no silver-layer peel, no lead detachment, no encapsulation break, no side flashover | Failure def. |
| 2 | Varistor voltage | Post-aging U1mA within ±10% of initial (≥90%, ≤110%) | Failure / endurance ±10% |
| 3 | Standby leakage | Post-aging IL(0.75U1mA) ≤ initial and ≤ maker limit (≤50 μA rec., hard ≤1 mA) | Failure def. |
| 4 | α coefficient | α not significantly degraded (≥25 rec., or drop ≤30% of initial) | IEC 61051-2 ref. |
| 5 | Clamping voltage | Post-aging clamping voltage change ≤ ±10% of initial | Failure def. |
| 6 | Online thermal | Leakage/power must not rise monotonically to supply/thermal limit (no thermal runaway) | Endurance spirit |
5. Test Data & Analysis
5.1 Online leakage characteristic
The three samples’ online leakage started at 134 / 118 / 124 μA and, as interface states relaxed, monotonically decreased and stabilized within about one week at 48 / 40 / 43 μA — strictly decreasing/steady with no rebound or loss of control. Corresponding power dropped from ~153 / 135 / 141 mW to ~55 / 46 / 49 mW.
Two power-off interruptions occurred (power upgrade 116 h; typhoon 160 h). Stress paused and, after re-energizing, leakage continued its prior steady trend with no anomalous step. Online thermal stability therefore satisfies Criterion 6.
5.2 Pre/Post 3-parameter comparison
Table 5-1 gives the pre- and post-aging (primary) 3-parameters of the three samples. Post-aging U1mA rose slightly (+1.4% to +2.8%) instead of dropping, well within the ±10% band; standby leakage IL(0.75U1mA) fell from 3.1–3.7 μA to 2.6–3.1 μA; α rose from 30–32 to 35–38 — all better than pre-aging. A second post-recovery measurement (longer cooling) shows U1mA up to 1452–1461 V, IL down to 1.3–1.6 μA, α up to 61–63 — a further recovery trend, also fully compliant.
| # | Stage | U1mA (V) | ΔU1mA | IL(0.75U1mA) (μA) | α |
|---|---|---|---|---|---|
| 1 | Pre | 1374.0 | — | 3.7 | 30.7 |
| 1 | Post (primary) | 1398.7 | +1.8% | 3.1 | 35.0 |
| 1 | Post-recovery | 1455.7 | +5.9% | 1.5 | 61.0 |
| 2 | Pre | 1371.0 | — | 3.38 | 29.9 |
| 2 | Post (primary) | 1409.2 | +2.8% | 2.7 | 37.5 |
| 2 | Post-recovery | 1461.0 | +6.6% | 1.6 | 62.6 |
| 3 | Pre | 1374.7 | — | 3.1 | 32.4 |
| 3 | Post (primary) | 1393.5 | +1.4% | 2.6 | 35.5 |
| 3 | Post-recovery | 1452.0 | +5.6% | 1.3 | 63.2 |
Note: ΔU1mA is vs. primary post-aging value; worst case (post-recovery) +5.6% to +6.6% still below the +10% limit.
6. Conclusion
| Sample | ΔU1mA | IL(0.75U1mA) post | α post | Online thermal | Verdict |
|---|---|---|---|---|---|
| #1 | +1.8% (≤±10%) | 3.1 μA (≤50 μA) | 35.0 (≥25) | Stable | PASS |
| #2 | +2.8% (≤±10%) | 2.7 μA (≤50 μA) | 37.5 (≥25) | Stable | PASS |
| #3 | +1.4% (≤±10%) | 2.6 μA (≤50 μA) | 35.5 (≥25) | Stable | PASS |
Overall Result
The three MDAY 34S132K samples completed 997 h effective DC aging at 115 °C / 1140 V (≡ Uc), meeting Clause 8 of GB/T 18802.331-2024. All metrics satisfy the acceptance criteria: ΔU1mA +1.4% to +2.8% (≤ ±10%), standby leakage 2.6–3.1 μA (≤50 μA), α 35–38 (≥25), online leakage steadily stable with no thermal runaway, and structure intact.
Verdict: PASS — the MOV demonstrates ample long-term stability and life margin under sustained voltage and high temperature.
7. Competitor Comparison (Historical Data)
The test basis and acceptance criteria are the same as Chapters 1–4 (GB/T 18802.331-2024); this chapter focuses on the comparison data and conclusion. The competitor is anonymized as “Competitor 34S132K”; in-house is “MDAY 34S132K”. Note: the in-house sample in this comparison (tester Wei Liyong, DC 1140 V, stopped at ~160 h by typhoon, passed) is the same model/condition early partial run later completed to 1000 h in this report.
7.1 Overview & condition comparison
| Item | Competitor (34S132K) | In-house (MDAY 34S132K) |
|---|---|---|
| Model | 34S132K (supplied) | 34S132K (in-house) |
| Tester | Shi Guoneng | Wei Liyong |
| Temp. | 115 °C | 115 °C |
| DC voltage | 1124 V | 1140 V |
7.2 Online leakage comparison
Competitor (left): two-channel leakage rose monotonically from 262 / 222 μA to 670 / 1330 μA; power rose from ~295 / 250 mW to 753 / 1495 mW with no stabilization. At ~32 h, the rising power tripped the supply protection — a classic thermal-runaway failure.
In-house (right): three-channel leakage relaxed from 106 / 110 / 73 μA and stabilized at ~52 / 48 / 37 μA, strictly decreasing/steady with power falling in step, no loss of control. Aging was stopped at 160 h by typhoon “White Dolphin”, not by product failure.
7.3 Pre/Post 3-parameter comparison
Table 7-2. Competitor (34S132K) pre/post 3-parameter:
| # | Stage | U1mA (V) | ΔU1mA | IL(0.75U1mA) (μA) | α |
|---|---|---|---|---|---|
| 1 | Pre | 1359.0 | — | 3.7 | 51.7 |
| 1 | Post | 1139.0 | -16.2% | 87.0 | 9.0 |
| 2 | Pre | 1386.0 | — | 5.0 | 55.4 |
| 2 | Post | 1053.7 | -23.9% | 138.0 | 7.0 |
| 3 | Pre-screen | 1159.0 | — | 66.8 | 10.0 |
| 3 | Result | — | — | not aged (failed pre-screen) | — |
Note: sample #3 pre-screen IL(0.75U1mA) = 66.8 μA already exceeds the 50 μA internal limit and α = 10 — failed incoming screening, never aged.
Table 7-3. In-house (MDAY 34S132K) pre/post 3-parameter:
| # | Stage | U1mA (V) | ΔU1mA | IL(0.75U1mA) (μA) | α |
|---|---|---|---|---|---|
| 1 | Pre | 1374.0 | — | 3.7 | 30.7 |
| 1 | Post | 1368.7 | -0.4% | 5.0 | 27.7 |
| 2 | Pre | 1371.0 | — | 3.38 | 29.9 |
| 2 | Post | 1374.0 | +0.2% | 4.4 | 29.3 |
| 3 | Pre | 1374.7 | — | 3.1 | 32.4 |
| 3 | Post | 1370.0 | -0.3% | 4.2 | 29.3 |
7.4 Competitor comparison conclusion
| Sample | ΔU1mA | IL(0.75U1mA) post | α post | Online thermal | Verdict |
|---|---|---|---|---|---|
| Comp. #1 | -16.2% (>10%) | 87 μA (over limit) | 9.0 (collapse) | Runaway | FAIL |
| Comp. #2 | -23.9% (>10%) | 138 μA (over limit) | 7.0 (collapse) | Runaway | FAIL |
| Comp. #3 | — (not aged) | 66.8 μA pre (over) | 10 (low) | — | Screen fail |
| In-house #1 | -0.4% | 5.0 μA | 27.7 | Stable | PASS |
| In-house #2 | +0.2% | 4.4 μA | 29.3 | Stable | PASS |
| In-house #3 | -0.3% | 4.2 μA | 29.3 | Stable | PASS |
Overall:
The competitor ―34S132K‖ suffered thermal runaway and tripped the supply at ~32 h; post-aging U1mA dropped 16%~24%, standby leakage spiked to 87~138 μA, α collapsed from ~50 to 7~9, and sample #3 even failed incoming screening — verdict FAIL. The in-house ―MDAY 34S132K‖ ran 160 h with steady leakage, no runaway, ΔU1mA ≤±0.5%, IL 4~5 μA, α 27~33, fully meeting criteria — verdict PASS. Conclusion: under same-spec DC accelerated aging, the in-house product shows significantly better high-temperature long-term stability and life margin; recommend full-batch retest and supplier quality traceability for the competitor lot.
