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SmartCockpit Q400 Manual

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12.5
(ATA 24) ELECTRICAL POWER
12.5.1
Introduction
The Electrical Power Generation and Distribution System (EPGDS) is used to supply the electri-
cal energy for all onboard electrical equipment. The EPGDS has DC and AC generating sys-
tems. The DC generation system includes a battery system. The EPGDS provides for energy
conversion, distribution, storage, control, protection, monitoring, and indication to the flight crew.
Provision is made for external connection of DC or AC external power while on the ground.
12.5.2
General
The DC generation system is supplied by three NiCad batteries, two engine driven starter/gener-
ators, two Transformer Rectifier Units (TRUs) and an optional Auxiliary Power Unit (APU). The
TRUs supply 28VDC and are powered by two engine driven Alternating Current (AC) generators
that supply 115Volts Alternating Current (VAC).
The power is distributed by an electrical bus system. It re configures for individual power source
and bus failures, by the automatic closing and opening of bus tie contactors.
There are both DC and AC external power receptacles for Ground Power Unit (GPU) connection.
All AC and DC aeroplane services can be operated from the AC generators or the AC external
power alone.
Dash8 - Q400 - Electrical
Page 1

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Summary of Contents for SmartCockpit Q400

  • Page 1 Dash8 - Q400 - Electrical 12.5 (ATA 24) ELECTRICAL POWER 12.5.1 Introduction The Electrical Power Generation and Distribution System (EPGDS) is used to supply the electri- cal energy for all onboard electrical equipment. The EPGDS has DC and AC generating sys- tems.
  • Page 2 Dash8 - Q400 - Electrical 12.5.3 Controls and Indications - Electrical Power Page 2...
  • Page 3 Dash8 - Q400 - Electrical ELEC FUEL DOORS TEST MFD2 MFD1 NORM NORM ED BRT EFIS EFIS ATT/HDG SOURCE SOURCE Figure 12.5-1 Engine and System Integrated Displays Control Panel (ESCP) ESCP CALLOUTS PERTAINING TO ELECTRICAL ITEMS 1. ELEC SYS PUSHBUTTON (momentary action)
  • Page 4 Dash8 - Q400 - Electrical DC CONTROL BATTERY STBY MAIN BATT BATT MASTER BATT GEN 1 GEN 2 MAIN BUS BUS FAULT EXT PWR RESET Figure 12.5-2 DC Control Panel (1 of 3) Page 4...
  • Page 5 Dash8 - Q400 - Electrical DC CONTROL PANEL CALLOUTS 1. STBY BATT switch (two position) STBY BATT - left main feeder bus charging circuit connected to standby battery EPCU logic inhibits this connection under the following conditions: • with external power (no charge) option •...
  • Page 6 Dash8 - Q400 - Electrical DC CONTROL BATTERY STBY MAIN BATT BATT MASTER BATT GEN 1 GEN 2 MAIN BUS BUS FAULT EXT PWR RESET Figure 12.5-3 DC Control Panel (2 of 3) Page 6...
  • Page 7 Dash8 - Q400 - Electrical DC CONTROL PANEL CALLOUTS (cont’d) 4. BATTERY MASTER SWITCH (two position, lever locked at OFF) BATTERY MASTER any battery is capable of powering both essential buses switch control is hard wired and independent of EPCU operation...
  • Page 8 Dash8 - Q400 - Electrical DC CONTROL BATTERY STBY MAIN BATT BATT MASTER BATT GEN 1 GEN 2 MAIN BUS BUS FAULT EXT PWR RESET Figure 12.5-4 DC Control Panel (3 of 3) Page 8...
  • Page 9 Dash8 - Q400 - Electrical DC CONTROL PANEL CALLOUTS (cont’d) 8. DC EXT PWR SWITCH EXT PWR - left and right main feeder buses, essential buses and secondary buses powered from DC external power source DC and APU generators are inhibited from connection to feeder buses...
  • Page 10 Dash8 - Q400 - Electrical AC CONTROL GEN 1 GEN 2 Figure 12.5-5 AC Control Panel Page 10...
  • Page 11 Dash8 - Q400 - Electrical AC CONTROL PANEL 1. EXTERNAL POWER SWITCH (two position) EXT PWR - connects AC external power to variable frequency buses is capable of powering all AC and DC buses on the aeroplane isolates the AC generators from the buses...
  • Page 12 Dash8 - Q400 - Electrical ELECTRICAL DC EXT AC EXT PWR ON PWR ON APU GEN AC GEN 1 BATT LOAD °C LOAD VOLT LOAD +1. 00 +1. 00 . 06 1 1 5 MAIN 1 1 5 . 06 - .
  • Page 13 Dash8 - Q400 - Electrical MULTI FUNCTION DISPLAY (MFD) ELECTRICAL PAGE CALLOUTS 1. DC EXT POWER ANNUNCIATOR (green) displayed when a DC external power source is connected to the aeroplane and supply- ing DC power within voltage tolerances 2. BATTERY LOAD AND TEMPERATURE ANNUNCIATION AREA BATT (white) LOAD, °C (cyan)
  • Page 14 Dash8 - Q400 - Electrical ELECTRICAL DC EXT AC EXT PWR ON PWR ON APU GEN AC GEN 1 BATT LOAD °C LOAD VOLT LOAD +1. 00 +1. 00 . 06 1 1 5 MAIN 1 1 5 . 06 - .
  • Page 15 Dash8 - Q400 - Electrical MULTI FUNCTION DISPLAY (MFD) ELECTRICAL PAGE CALLOUTS (cont’d) 6. DIGITAL DISPLAY OF DC BUS VOLTAGE (white) indicates the voltage on the associated bus 7. DIGITAL DISPLAY OF APU GENERATOR LOAD (white) APU GEN (white) LOAD (cyan)
  • Page 16 Dash8 - Q400 - Electrical ELECTRICAL DC EXT AC EXT PWR ON PWR ON APU GEN AC GEN 1 BATT LOAD °C LOAD VOLT LOAD +1. 00 +1. 00 . 06 1 1 5 MAIN 1 1 5 . 06 - .
  • Page 17 Dash8 - Q400 - Electrical MULTI FUNCTION DISPLAY (MFD) ELECTRICAL PAGE CALLOUTS (cont’d) 11. DIGITAL DISPLAY OF AC GENERATOR LOAD (white) the load demand on the AC generator is displayed in the following format: • “+” sign is displayed on the left of the lead digit to indicate an overload of the AC power source •...
  • Page 18 Dash8 - Q400 - Electrical Figure 12.5-9 Pilot’s Lower Circuit Breaker Panel Page 18...
  • Page 19 Dash8 - Q400 - Electrical Figure 12.5-10 Pilot’s Upper Circuit Breaker Panel Page 19...
  • Page 20 Dash8 - Q400 - Electrical Figure 12.5-11 Copilot’s Lower Circuit Breaker Panel Page 20...
  • Page 21 Dash8 - Q400 - Electrical Figure 12.5-12 Copilot’s Upper Circuit Breaker Panel Page 21...
  • Page 22 Dash8 - Q400 - Electrical Figure 12.5-13 DC Power Electrical Schematic - Fully Operational Page 22...
  • Page 23 Dash8 - Q400 - Electrical Page 23...
  • Page 24 Dash8 - Q400 - Electrical 12.5.4 Detailed Description The Electrical Power Generation and Distribution System (EPGDS) (Figure 12.5-13) has an Electrical Power Control Unit (EPCU) to control, monitor and distribute DC power to the aeroplane’s electrical buses. The EPCU automatically re configures the EPGDS for power source and bus failures, by the closing and opening of bus ties contactors.
  • Page 25 Dash8 - Q400 - Electrical 12.5.6.1 Batteries The main and auxiliary 24-volt NiCad batteries are located in the lower left nose compartment. The main and auxiliary batteries have a 40-amp-hour capacity. The standard standby 17-amp- hour battery (optional 40-amp-hour) is located in the tail compartment, when no APU is installed.
  • Page 26 Dash8 - Q400 - Electrical The charge characteristics of the 40 Ahr batteries are as follows: Discharging Characteristics - The 40 Ahr batteries have a nominal voltage of 24 VDC (20 cells at 1.2 VDC/cell). This is the voltage that would be measured with a fully charged battery under a load equal to its ampere-hour rating, i.e.
  • Page 27 Dash8 - Q400 - Electrical Figure 12.5-15 DC Power System Battery Power Only Page 27...
  • Page 28 Dash8 - Q400 - Electrical 12.5.6.2 Starter/Generators The starter/generators are located on the accessory gearbox of each engine. Each starter/gener- ator serves as a starter motor and will revert to generator operation if the DC GEN switch is in the ON position and the engine speed exceeds 50% NH following successful engine start.
  • Page 29 Dash8 - Q400 - Electrical 12.5.6.5 Fault Tolerant Operation The DC Power subsystem is extremely tolerant to power source failures. It has four separate sources of DC power in flight. They are the two generators and two TRUs. When all DC power sources are operational, each source powers its own dedicated bus.
  • Page 30 Dash8 - Q400 - Electrical 12.5.6.7 Main Bus Failures If a main bus fault occurs, the EPCU prevents the upper horizontal and two vertical bus ties from closing, isolating the bus. The DC BUS caution light comes on to warn of the fault impending condition.
  • Page 31 Dash8 - Q400 - Electrical 12.5.6.9 Engine Starting The starting process is initiated by selecting an engine position using the SELECT switch from the Engine Start control panel. The starting process is initiated by depressing the START button. The power source (which feeds the main buses for the supply of the starter/generator) for the starting process can be different.
  • Page 32 Dash8 - Q400 - Electrical OPEN CLOSED fs number Figure 12.5-16 DC External Power Receptacle Page 32...
  • Page 33 Dash8 - Q400 - Electrical c) Starting from DC External Power A Ground Power Unit (GPU) can be connected to the DC external power receptacle (Figure 12.5-16) on the left side of the forward fuselage. The GPU can supply DC power for the aeroplane EPGDS and for engine starting (Figure 12.5-17).
  • Page 34 Dash8 - Q400 - Electrical Figure 12.5-17 External DC Power Schematic Page 34...
  • Page 35 Dash8 - Q400 - Electrical 12.5.7 AC System The AC electrical schematic is shown in Figure 12.5-18. Electrical power sources for the AC portion of the EPGDS include: • Two alternating current variable frequency generators • AC External The power sources supply power to the following buses in order of priority: •...
  • Page 36 Dash8 - Q400 - Electrical Page 36...
  • Page 37 Dash8 - Q400 - Electrical GROUND POWER A.C. 115V Figure 12.5-19 AC External Power Receptable Page 37...
  • Page 38 Dash8 - Q400 - Electrical 12.5.7.2 AC External Power Location of the AC Ground Power Connection A GPU can be connected to the AC external power receptacle on the forward right hand fuselage near the nose cone (Figure 12.5-19), to supply AC power to the aeroplane.