Power Distro / PDU
Definition
A power distribution unit (distro or PDU) takes one large incoming supply, single-phase or three-phase, and divides it into many individually protected outputs. In Europe, a touring distro commonly takes a 63 A or 125 A IEC 60309 (CEE) input and feeds 16/32 A outlets or Socapex multicores, each circuit protected by a circuit breaker and usually an RCD, with voltage and current metering per phase. North American distros commonly take their feeders on single-pole cam-type connectors and supply 120 V circuits. On a three-phase supply, spreading the load evenly across L1/L2/L3 keeps the phase currents similar; the neutral current also depends on the harmonics drawn by electronic loads.
In the field
The load is balanced across the three phases before the show, because an unbalanced distro can trip one phase at peak load while the other two are lightly loaded. The main isolator and the RCD test buttons are located before they are needed, and the incoming voltage on each phase, as well as between neutral and earth, is measured and recorded at connection.
Sources
- IEC 60309 (Wikipedia, pointeur secondaire) : calibres 16, 32, 63 et 125 A des prises industrielles · en.wikipedia.org
- BS 7909:2023+A1:2024, installations électriques temporaires du spectacle en 230 V et 400 V 50 Hz : gestion, conception, mise en place et exploitation · knowledge.bsigroup.com
- Amphenol Socapex, Entertainment : connecteurs Soca pour l'éclairage scénique et la distribution électrique de spectacle · amphenol-socapex.com
- Electrical Installation Guide, Sizing the neutral conductor : courant de neutre dû aux harmoniques · electrical-installation.org