Electrical System - A few observations
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Hi everyone,
first of all: I’m really enjoying this aircraft and have spent a lot of time in the cockpit over the past few days. The 146 is just a special airplane and it’s a real pleasure to fly. Big kudos to the developers for the work that went into this!I’ve been taking a closer look at the electrical system and doing some testing on the ground. I came across a few things I’d like to share, hopefully it’s useful for further refinement.
- BATT OFF LINE Annunciator on Manual Deselection
When the batteries are manually switched OFF during normal operation (EXT AC on the busbars, TRs running), no BATT 1/2 OFF LINE annunciator appears. According to the manual, these should illuminate since the battery contactors are open and the batteries are no longer connected to EMERG DC. The warning lights busbar is powered via DC BUS 2 and EMERG DC, so the annunciators should have power.
- AC Priority: APU GEN vs. EXT AC
I know the normal procedure calls for starting the APU and selecting APU GEN on before using EXT AC, and that the manual says to select APU GEN OFF/RESET if starting using EXT AC. So in normal operations you’d typically use one or the other. Still, I was curious and tested what happens when both are available at the same time.
With EXT AC already on the busbars, I switched the APU GEN on. The APU GEN immediately took over and displaced EXT AC. To my understanding of the 146 Operations Manual, it should be the other way around: EXT AC has priority over APU GEN. The manual also states that the APU GEN OFF LINE annunciator illuminates when „EXT AC power has taken precedence in supporting the AC busbars,” which seems to confirm that EXT AC should take priority.
I believe the priority order for Channel 1 should be:
1. GEN 1
2. EXT AC
3. APU GEN
4. GEN 4 (with bus-tie AUTO)
On top of that, when the APU GEN is then switched to OFF/RESET with the GPU still connected and available (EXT AC PWR AVAILABLE green), the system does not fall back to EXT AC. Instead, all AC and DC busbars are lost and EXT AC has to be manually reselected.
Either the priority logic differs from what the 146 Operations Manual describes, or there may be an issue with the bus-tie and transfer implementation. Happy to be corrected if I’m reading the manual wrong!Things that are correctly simulated and work as expected:
∙ ESS DC supply via START MASTER (ESS/EMERG ACO forced closed – ESS DC OFF extinguishes)
∙ TR charging logic (batteries correctly charged via EMERG DC, positive charge current shown on battery ammeter)
∙ DC voltmeter and meter selectors work correctly
∙ Basic busbar supply and AC instruments (115V, 400 Hz)
∙ STBY GEN starts automatically on loss of both AC busbars (ARM position)Once again: great work overall! This is not meant as criticism of the package as a whole. Looking forward to future updates.