Three-phase PDU load balancing basics
Balance is a per-phase current comparison read on one scale. The unit reports 0.1A steps at ±1% plus one digit, so an uneven row shows up on the next poll rather than at the breaker.
- Total current
- 0.1A step
- Accuracy
- ±1% + 1 digit
- Example unit
- 20 × 20A (SA-20)
- Working voltage
- AC 415V
- Phases read
- L1 · L2 · L3
Three-phase figures
What each reading on a three-phase feed is published at
The step and the tolerance are fixed for the series. Everything a balance check compares comes from these rows.
| Item | Published value | What it fixes |
|---|---|---|
| Total current scale | 0.1A | The step each feed current is reported at |
| Current accuracy | ±1% + 1 digit | How close one reading sits to the line it is taken on |
| Phase reading | L1 · L2 · L3 | Which line a current value belongs to |
| Model example | 20 × 20A (SA-20) | Outlet count and rating on one chassis |
| Working voltage | AC 415V | The three-phase build the unit is ordered for |
| Frequency | 50Hz~60Hz | The supply band at the rack |
| Voltage scale | 1V · 90V to 350V | The window the meter publishes voltage over |
| Active power | ±1% per feed | Which feed a measured load is attributed to |
| Energy total | 1 grade · 0.1 kWh | The billing row kept on each reporting line |
| Outlet branch | 10A–16A | The rating at each outlet position |
| Breaker | one per feed | The isolation point for a row taken out of service |
| Remote switching | per outlet or per group | Moving a load without a site visit |
| Ambient sensor | -30°C to 100°C | Rack inlet temperature at 1°C resolution |
| Event store | up to 20,000 | Dated record of threshold crossings |
Balance check
What goes into one comparison
- Lines comparedL1 · L2 · L3
- Step per line0.1A
- Tolerance±1% + 1 digit
- Isolationbreaker per feed
- Move a loadper outlet or group
Mechanism
Balance is a comparison, not a target
A three-phase feed is balanced when the phase currents sit close to each other at the load the rack actually draws. Each line is published at a 0.1A step on the same scale, so the check is a subtraction rather than an estimate.
Because every line is read on the same meter, moving an outlet from a loaded line to a light one changes both figures on the next poll. Active power is attributed per feed at ±1%, and the energy total keeps its 1 grade step through the move. A breaker sits at each feed, which is also the point where a row is isolated for service. Where a rack draws unevenly, the readings show it long before the current reaches the breaker, and remote switching on a switched build moves the load without a site visit.
- Lines read
- L1 · L2 · L3
- Step
- 0.1A
- Tolerance
- ±1% + 1 digit
- Isolation
- breaker per feed
-
One scale for all three lines. At a 0.1A step, a difference between phases is visible as a number rather than a guess.
-
The breaker is the last resort. Current readings on each line show the spread while it is still small enough to correct by moving an outlet.
-
Per-outlet switching moves the load. On a switched build an outlet can be cycled or reassigned without a site visit.
Phase view
The values a balance check is built from
Each cell is one published value on the reporting line, at the scale a platform receives it on.
Total current
0.1A
Reported per feed, and per phase where the build is metered that way.
Accuracy
±1% + 1 digit
The tolerance behind every phase comparison.
Working voltage
AC 415V
The three-phase build the unit is ordered for.
Frequency
50Hz~60Hz
The supply band at the rack.
Example unit
SA-20
Outlet count and rating example: 20 × 20A on one chassis.
Energy total
0.1 kWh
Kept at 1 grade on each reporting line.
Ambient sensor
-30°C
Range to 100°C at 1°C resolution at the rack inlet.
Isolation
per feed
One breaker per feed, and remote switching per outlet or group.
Request a quote
Send the feed and the phase readings you have
Current per feed, outlet combination, metering depth and remote switching. The reply carries the phase arrangement and a per-line specification sheet, in English.
Reply within 12 hours on working days. No lead time and no minimum quantity figure is published on this site.
