DC Arc Flash Measurements From a 1000 V Valve Regulated Lead Acid Battery System
IEEE Open Journal of Industry Applications (Institute of Electrical and Electronics Engineers (IEEE)) · Nicolaus Jennings, David Wetz et al.
An IEEE Open Journal of Industry Applications paper in which EPRI and the University of Texas at Arlington measured DC arc flash from VRLA battery strings up to 936 V and compared results with three calculation models.
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Overview
This paper by Nicolaus Jennings, David Wetz, Rick Langley, Nancy LaFlair and John Heinzel, published in the IEEE Open Journal of Industry Applications in 2024 (vol. 5, pp. 168-176), presents measurements made by EPRI and the University of Texas at Arlington. DC arc flash was measured from VRLA lead-acid battery strings at up to 936 V (one and two strings), recording arc voltage, current, duration and incident energy. The authors note that medium and large UPS battery systems typically operate at 380 VDC.
The results are compared with three approaches: the NFPA 70E maximum-power model, Ammerman's arc-power model and a fraction-of-bolted-fault-power fit. Below 800 V the VRLA battery produced incident energy up to 0.26 cal/cm2; above 800 V incident energy exceeded 1.2 cal/cm2 and approached the 4 cal/cm2 category 1 PPE level because arcs lasted longer. These figures show that PPE need does not scale smoothly with system voltage, because arc duration also changes.
The maximum-power model was found inconsistent: for a single string it underestimates incident energy below 500 V and strongly overestimates above 500 V. The largest maximum-power estimate was 11.21 cal/cm2 against a measured 3.67 cal/cm2. Ammerman's model matched best. Average arc power was fitted at about 16% of the bolted-fault power; matching an open-air bolted-power model to measurements needed a scale factor of 0.5, suggesting the enclosure absorbed about half the energy, so enclosure multipliers could make PPE overly conservative. As a limit, the study is confined to VRLA battery strings and its particular test conditions.
Key points
- Below 800 V the VRLA battery produced incident energy up to 0.26 cal/cm2; above 800 V incident energy exceeded 1.2 cal/cm2 and approached the 4 cal/cm2 category 1 PPE level.
- The authors note that medium and large UPS battery systems typically operate at 380 VDC.
- The largest maximum-power estimate was 11.21 cal/cm2 against a measured 3.67 cal/cm2; for a single string the model underestimated below 500 V and overestimated above 500 V.
- Average arc power was fitted at about 16% of the bolted-fault power.
- Matching an open-air bolted-power model to measurements needed a scale factor of 0.5; the enclosure may have absorbed about half the energy, so enclosure multipliers could make PPE overly conservative.
- Ammerman's arc-power model matched the measurements best.
Using it in design
- For UPS battery arc-flash checks at 380-1000 VDC, expect incident energy to rise sharply with voltage and arc duration above roughly 500-800 V.
- Have the calculator report the method choice (maximum power vs Ammerman).
- Warn that the maximum-power method can under-predict at lower voltages and should not be treated as a guaranteed upper bound.
- When judging the enclosure effect on PPE selection, consider the measurement-based data.
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Who should read it
Electrical engineers performing DC arc-flash studies of data centre UPS battery systems and safety officers who set PPE levels.
Related standards
- NFPA 70E
Publication details
- Authors
- Nicolaus Jennings; David Wetz; Rick Langley; Nancy LaFlair; John Heinzel
- Publisher
- IEEE Open Journal of Industry Applications (Institute of Electrical and Electronics Engineers (IEEE))
- Year
- 2024
- Volume
- 5
- Pages
- 168-176
- Document language
- English
- Source type
- Scientific
- Access
- Free to read
- Licence
- CC BY-NC-ND 4.0 — share unaltered with attribution for noncommercial purposes
Original licence note
Article states CC BY-NC-ND 4.0; non-commercial/no-derivatives, so citation only.
Citation
Nicolaus Jennings; David Wetz; Rick Langley; Nancy LaFlair; John Heinzel (2024). DC Arc Flash Measurements From a 1000 V Valve Regulated Lead Acid Battery System. IEEE Open Journal of Industry Applications (Institute of Electrical and Electronics Engineers (IEEE)). 5, 168-176. https://doi.org/10.1109/OJIA.2024.3400208
Events on this subject
- Electricity Eurasia 2027
- ELECO 2026 Elektrik-Elektronik ve Biyomedikal Mühendisliği Konferansı
- 7x24 Exchange Spring Conference
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