Emergency lighting power supplies
Effectivity: Global 7500 aircraft
ATA 24
The Emergency Lighting System provides emergency lighting to allow passengers and crew to evacuate the aircraft quickly and safely in an emergency.
The Global 7500 Emergency light system is very similar to the Global Express system containing an EMER LIGHTS control toggle switch located on the flight deck overhead panel, four Emergency Light Power Supplies (ELPS), Exterior and Interior Emergency lights.
The ELPS, powered from the DC ESS BUS 1, providing emergency lights power for a minimum of 15 minutes when fully charged. The ELPS monitors the 28 VDC aircraft input power and provide the power to the Emergency lights in case were the 28Vdc become unavailable after the EMER LIGHTS toggle switch have been put to ARM.
Within each ELPS, a battery management circuit control the battery pack health:
1. Quick-charge-mode: This mode recharging the battery pack until the battery is full for a maximum of 90 minutes. The battery charge starts with a current of 60 mA and only start when battery voltage is more than +5 Vdc. The quick charge current level is up to 1.7 A.
2. Trickle Charge Mode: When not in Quick-Charge-Mode, the trickle charge mode is active and consists of maintaining the battery charge by applying a constant current of approximative 10mA to the battery pack.
Please note that the ELPS does not recharge when the EMER LIGHTS is in the ON position.
3. Battery Heating: Monitors & heats the battery to an optimal operating temperature of 22 °C.
The Global 7500 OMS real-time page allows maintenance personnel to monitor in real-time the ELPS load performance by looking at the Solid-State Power Controller (SSPC) output current knowing the current draw required by the ELPS is depending on their state.
See below the nominal ELPS current draw:
• Nominal (Trickle), battery heating off approx. 0.2 A
• Nominal (Trickle), battery heating on approx. 1.4 A
• Quick Charge, battery heating off approx. 1.0 A
• Quick Charge, battery heating on approx. 2.0 A
Note: The above values are for a single unit only & the OMS real-time page reading have a certain tolerance.
Getting familiar with the ELPS current draw behavior can help isolate issue and detect problem with ELPS in advance. It also can be used to make sure the quick charge completed and all 4 ELPS are in trickle charge mode.
The four ELPS are powered by two SSPC which are divided as follow:
• EMER LTS 1 - SSPC_ID_314 for the ELPS 1 & 3
• EMER LTS 2 - SSPC_ID_315 for the ELPS 2 & 4
Note: One SSPC current is the addition of two ELPS current load so reflecting the state of 2 ELPS together.
For Customer with the connected AHMS, both EMER LTS 1 & 2 SSPC current trend can be followed using both Labels SSPC_ID_314 for the ELPS 1 & 3 & SSPC_ID_315 for the ELPS 2 & 4.
