Reading the ECAM ELEC Page

The ELEC AC page is not one picture but three. FCOM splits its display description into FLIGHT, GROUND and EMER CONFIGURATION segments, and the page genuinely reflows between them: on the ground an external-power frame appears that is never shown in flight; in the emergency configuration the whole page is redrawn around the essential network. A page that changes shape is hard to read by memory, so this article does two things — it fixes the three "standard photographs" the page can take, and it gives a single scan order that reads any of them, however distorted, in a few seconds: who is supplying, where the corridor runs, and what state the bottom-of-ladder layer is in.

This sits at the end of the panels-and-display stage of the chapter, alongside Control Panels. The division of labour with Monitoring and Indication is worth fixing first: article 18 is the field dictionary — every IDG/GEN/TR threshold, every XX, every colour and its data source. This article is the page-level morphology — the overall shape in each configuration, the method for scanning it, and the two ELEC MEMOs. The fault chapters that follow (21–30) all describe their ECAM appearance against these three photographs, so they are the reference frame for the rest of ATA 24.

By the end you should be able to answer five questions:

1. What is the standard scan order for the ELEC AC page?
2. How do the flight and ground photographs differ?
3. In the emergency configuration, how do EMER GEN, STAT INV, SHED and LND RCVRY each appear?
4. What is the colour logic of the two ELEC MEMOs?
5. Where does the "connecting line" semantics come from — why does a line mean a current path exists?

1. The scan — four layers, bottom up

The ELEC AC page reproduces the physical logic of the single-line picture: sources at the bottom, main buses in the middle, the essential family on top, with the load-management message strip off to the side. Power flows up the page; in degradation the fall-back sources take over from the top down. Read it the way the power flows — bottom up — in four passes:

 read bottom-up ; power flows up  ▲
 ┌─ L4  MESSAGE STRIP (one white line, priority 1 = highest)
 │       1 COMMERCIAL OFF   2 GALLEY SHED   3 GALLEY PARTIALLY SHED
 ├─ L3  ESS FAMILY   AC ESS BUS ──ESS TR──►
 │       EMER GEN ►       ◄ STAT INV     (white triangles = standby)
 ├─ L2  MAIN BUSES   AC 1            AC 2      (green / amber)
 ├─ L1  SOURCES      GEN 1   APU GEN   GEN 2
 │       EXT A / EXT B   appear on ground only
 └──────────────────────────────────────────────────────────────

• L1 — the sources (GEN 1 / APU GEN / GEN 2; EXT A / EXT B on the ground). Are the three parameters in the box green? Which way does the supply arrow point — a green arrow means that source is feeding a bus.
• L2 — the main buses (AC 1, AC 2). FCOM gives the colour rule in one line:

  "The bus bar indication is normally green. It becomes amber, when the corresponding bar is not powered."

  Green bus = powered; amber bus = dead. This is the single most diagnostic colour on the page.
• L3 — the essential family (AC ESS BUS, the ESS TR arrow, and the two white standby triangles). Is AC ESS fed from AC 1 or AC 2? Are EMER GEN ► and ◄ STAT INV still white triangles on standby, or have they become live framed sources?
• L4 — the message strip. The load-management legend, shown in white, one line at a time by priority:

  "The following legend appears in white, when applicable, depending on the order of priority (1: highest priority): 1. COMMERCIAL OFF 2. GALLEY SHED 3. GALLEY PARTIALLY SHED."

  This tells you which of the three load-shed tiers the network is sitting in (see Galley and Commercial Loads). Priority 1 is the deepest shed.

Why a line means something. A connecting line drawn on the SD is the shadow of a closed contactor, not decoration. Among the ECMU's duties is "Monitoring and indicating"; it forwards each main contactor's position to the SDAC, and the System Display draws a connecting line wherever a contactor is closed (see ECMU and Contactor Management and Monitoring and Indication). So a line on screen = a closed contactor = a real current path. Where there is no line, the corridor is open.

2. Standard photograph 1 — the FLIGHT (normal) configuration

This is the baseline. Learn it cold, because any element that deviates from this photograph is the thing you have to explain.

   AC ESS BUS  ◄── fed from AC 1 (normal)
   EMER GEN ►          ◄ STAT INV          APU GEN  (white, no frame)
   ┌─────────┐                          ┌─────────┐
   │  AC 1   │   no corridor line       │  AC 2   │
   └────▲────┘   (split-bus)            └────▲────┘
        │                                    │
   ┌────┴────┐                          ┌────┴────┐
   │  GEN 1  │  load% · 116 V · 400 Hz  │  GEN 2  │
   └─────────┘                          └─────────┘

• The two main generators each show three parameters and feed straight up to their own bus by a short vertical link. On the read-image baseline (FCOM ELEC AC page, FLIGHT configuration) the GEN box carries a load percentage, 116 V and 400 Hz. The buses are split — the two IDGs are never paralleled, so there is no corridor line between AC 1 and AC 2.
• AC ESS BUS is fed from AC 1, its normal source (the AC ESS FEED is in NORM; see AC ESS Feed and Transfer).
• APU GEN sits white, no frame, no parameters — present but on standby.
• EMER GEN ► and ◄ STAT INV face each other as white standby triangles — armed but not running.
• The IDG box shows its oil outlet temperature (green in the normal range).
• DC side: the three TRs each supply their own network, and the batteries sit with no significant current — green, effectively no discharge arrow.

One detail of the GEN field that matters when a generator has been switched off. FCOM gives the full pushbutton-OFF / pushbutton-ON colour set:

"When the GEN pushbutton is OFF: (A) The GEN number is white, if the associated engine is running. It becomes amber, when the associated engine stops. (B) The GEN indication is amber. (C) The OFF indication is white. When the GEN pushbutton is ON: (A) The arrow indication is green, when the generator line contactor is in line. (B) The GEN number is white, if the associated engine is running. It becomes amber, when the associated engine stops. (C) The GEN indication is normally white. It becomes amber, when the generator fails, or when the associated engine stops. (D) The GEN load is normally green. It becomes amber, if the load is greater than 108 %, for more than 10 s."

Per FCOM DSC-24-20. So a GEN pb OFF shows the GEN number white (amber if that engine has stopped), the word GEN amber, and a white OFF — a deliberate selection, distinct from a failed generator. With the pb ON, the green arrow is the live confirmation that the line contactor is closed and the generator is on the bus. The field-by-field thresholds (108 % / 10 s load, 110–120 V, 390–410 Hz) are owned by GCU and AC Generation Control and the field dictionary.

3. Standard photograph 2 — the GROUND configuration

The ground page differs from the flight page in two ways: the external-power frames appear, and the APU GEN is shown framed with parameters when it is supplying. FCOM ties both to the on-ground state:

"(1) APU Generator … green when APU generator supplies one or more AC bus bar; white otherwise … same logic as engine generator. (2) External power A (External power B symbol appears beside with the same principle): (only displayed when aircraft is on ground) … green when external power supplies one or more bus bar; white otherwise."

Per FCOM DSC-24-20, GROUND CONFIGURATION. Two reading rules fall straight out:

• EXT A / EXT B are drawn only on the ground — see one in flight and something is wrong with the weight-on-wheels logic, not the electrics.
• For a ground source, green = supplying at least one bus bar, white = available but not supplying. The same green/white "supplying vs available" distinction the white standby triangles carry in flight.

A worked read-image (single engine running + APU, networks split). Reading the GROUND-configuration page at FCOM p.1695:

 GROUND read-image  (single engine + APU, split networks)
   ┌─────────┐        ┌─────────┐        ┌─────────┐
   │  GEN 1  │        │ APU GEN │        │  GEN 2  │
   │  62 %   │        │  72 %   │        │ 0 (off) │
   └────┬────┘        └────┬────┘        └─────────┘
        │ up to AC 1       │ branches up to AC 2
        ▼                  ▼
       AC 1               AC 2
   EXT A / EXT B frames shown (ground only), white = available

GEN 1 at 62 % feeds AC 1 directly; GEN 2 reads all zeros (its engine stopped); APU GEN at 72 % branches up into AC 2 — the textbook picture of "one engine started, the APU carrying the opposite half-network", with EXT A/B standing by white. This is exactly the kind of split the network-priority logic produces, made visible.

4. Standard photograph 3 — the EMER configuration

When both AC BUS 1 and AC BUS 2 are lost, the page is redrawn as an ESS-centred view: the dead main buses move to the background and the essential network with its emergency sources takes the foreground. FCOM gives the element-by-element logic:

"EMER CONFIGURATION. (1) Emergency Generator — When the emergency generator contactor is closed: (A) same logic as engine generator (B) green. When the EMER GEN Contactor is open: EMER GEN ► : It is white. EMER GEN: It becomes amber when faulty. (2) Static Inverter — Same logic as the emergency generator. (3) AC ESS BUS — It is normally green; It becomes amber when the bus is not supplied. (4) SHED Indication — It appears in amber, when AC ESS SHED BUS is not supplied. (5) LND RCVRY indication — Appears in green when LAND RECOVERY pushbutton is pressed."

Per FCOM DSC-24-20, EMER CONFIGURATION. Read as a table:

The principle that ties the sources together: whichever symbol carries parameters is the one feeding the ESS network; a white triangle is still on standby. So on entry to the configuration you read the page by asking "is EMER GEN a green framed box yet, or still a white triangle?" — that single distinction tells you whether the emergency layer is alive.

[!warning]- SHED amber is not a fault — it is the design doing its job

An amber SHED does not mean a sheddable-essential-bus failure. In the emergency configuration the AC ESS SHED BUS is deliberately dropped to protect the essential core (and, on the RAT-driven branch, it stays dropped). The amber legend is the system announcing a designed load-shed, not reporting a fault. Treat it as confirmation that the degradation ladder has stepped down as intended, not as a new failure to chase.

The DC page in the emergency configuration picks up two increments. The battery current field is read with the battery arrow convention (green = charging, amber = discharging), and FCOM fixes the threshold:

"(C) Current (charge or discharge): normally green; amber if discharge current is above 5 A."

Per FCOM DSC-24-20, ELEC DC ECAM page. In the emergency configuration the batteries are discharging to sustain the DC ESS network, so an amber discharge indication is the expected normal state here, not an anomaly. A connecting line then appears between DC ESS and the batteries — the shadow of the closed battery-tie contactors feeding DC ESS (see Batteries and the BCL). The full emergency-supply map (what each bus is fed by, and the Lost after 7 s DC BAT BUS note) is in the FCOM distribution table and is worked through in Emergency Electrical Configuration.

5. The two ELEC MEMOs

The ELEC chapter contributes two memos to the EWD, each a single line with its own colour logic:

"ELEC EXT PWR : This memo appears in green if external power is available. It becomes amber if more than one engine is running."

"EMER GEN : This memo appears in green when emergency generator is running."

Per FCOM DSC-24-20, MEMO display.

The value of the green EMER GEN memo is that it lets you confirm the emergency layer is alive from the EWD itself — in an EMER CONFIG you can verify "the emergency generator is running" with a glance at the memo line, without leaving the procedure to call up the SD ELEC page.

[!warning]- ELEC EXT PWR amber is a reminder, not a failure

When ELEC EXT PWR turns amber it has not detected a fault. It is flagging an operational condition — external power is still connected while more than one engine is running — i.e. "you should have disconnected ground power by now". The colour change is a procedural prompt, not a system caution; do not chase it as a defect.

Self-test

[!note]- Q1. What is the standard scan order for the ELEC AC page, and what does a connecting line mean?

Read bottom up in four passes: L1 sources (GEN 1 / APU GEN / GEN 2, plus EXT A/B on the ground — parameters green? supply arrow green?) → L2 main buses (AC 1 / AC 2 green if powered, amber if not) → L3 essential family (AC ESS feed source, plus the EMER GEN ► / ◄ STAT INV standby triangles) → L4 message strip (the white load-shed legend, one line by priority: COMMERCIAL OFF / GALLEY SHED / GALLEY PARTIALLY SHED). A connecting line is the shadow of a closed contactor — the ECMU forwards contactor positions to the SDAC and the SD draws a line wherever a contactor is closed, so a line means a real current path.

[!note]- Q2. How does the GROUND photograph differ from the FLIGHT photograph?

Two differences. (1) The EXT A / EXT B frames appear — "only displayed when aircraft is on ground" — and never show in flight. (2) The APU GEN is drawn framed with parameters when it is supplying. For both ground sources the colour rule is green = supplying one or more bus bars, white = available but not supplying. The read-image at p.1695 shows the split case: GEN 1 62 % into AC 1, GEN 2 at zero (engine stopped), APU GEN 72 % branching up into AC 2.

[!note]- Q3. In the EMER configuration, how do EMER GEN, STAT INV, SHED and LND RCVRY appear?

EMER GEN and STAT INV follow the engine-generator principle: contactor closed → framed with parameters, green; contactor open → a white triangle (EMER GEN ►), turning amber if faulty — whichever has parameters is the one feeding the ESS network. SHED is an amber legend meaning AC ESS SHED BUS is not supplied (a by-design shed, not a fault). LND RCVRY is a green legend meaning the LAND RECOVERY pushbutton has been pressed (recovery completed). AC 1 and AC 2 are both amber — the reason you are in this configuration.

[!note]- Q4. What is the colour logic of the two ELEC MEMOs?

ELEC EXT PWR: green when external power is available; amber when more than one engine is running (a prompt to disconnect ground power, not a failure). EMER GEN: green when the emergency generator is running — used to confirm the emergency layer is alive from the EWD without switching to the SD ELEC page.

[!note]- Q5. What are the DC-page increments in the emergency configuration?

The battery current field, normally green, goes amber when discharge current exceeds 5 A — and in the emergency configuration the batteries are discharging to sustain DC ESS, so an amber discharge indication is the expected state, not an anomaly. A connecting line also appears between DC ESS and the batteries — the shadow of the closed battery-tie contactors feeding DC ESS.

Key takeaways

References

Per FCOM DSC-24-20 (ELEC AC ECAM page — FLIGHT configuration IDG/GEN field colours with the GEN pb OFF/ON logic, bus-bar colour, galley three-tier legend; GROUND configuration APU GEN and external-power "only displayed when aircraft is on ground"; EMER configuration EMER GEN / STAT INV / AC ESS BUS / SHED amber / LND RCVRY green; ELEC DC page battery charge-or-discharge colour with the 5 A threshold; the two MEMO-display lines ELEC EXT PWR and EMER GEN); FCOM DSC-24-10-30-40 (EMER CONFIG distribution table — emergency-supply map and the Lost after 7 s DC BAT BUS note, cross-referenced to article 29). The four-layer scan order is an integrative synthesis of the page layout against the single-line picture; the "a line is the shadow of a closed contactor" reading draws on the ECMU monitoring-and-indicating function established in article 06 and article 18. The read-images at p.1690 (flight baseline) and p.1695 (single-engine + APU split) are figure readings of the FCOM ELEC AC page.

Independent study material, not an Airbus publication. Refer to current operator FCOM, FCTM, and QRH for operational use.