190-01115-01 G3X/G3X Touch Installation Manual - Installation PreparationRev. AC Page 2-12Day VFR conditions. In case of an electrical system failure, or in the unlikely event of an issue with theG3X system, backup instruments should at minimum provide a secondary reference for aircraft attitude,airspeed, and altitude.The G5 standby flight display is designed as a complementary backup instrument for the G3X system. Itfeatures dissimilar hardware and software design to eliminate common-mode failures, supports an optionalbuilt-in backup battery, and synchronizes data such as baro setting and selected heading with the G3Xsystem. In conjunction with a GMC mode control panel, the G5 is also capable of driving the GSA 28autopilot servos even if power is removed from all GDU displays. For further information, refer to the G5installation/operation manual (190-02072-00).2.2 Electrical ConsiderationsThis section presents information required for planning the electrical layout of the G3X installation.CAUTIONTo avoid damage to the LRUs, take precautions to prevent Electro-Static Discharge (ESD)when handling connectors and associated wiring. ESD damage can be prevented bytouching an object that is of the same electrical potential as the LRU before handling theLRU itself.2.2.1 Power SpecificationsAll G3X LRUs are capable of operating at either 14 or 28 VDC (except the GAD 27 which is 14 VDConly, and the GAP 26, see Note in Section 5). Table 2-1 and Table 2-2 list supply voltage and current drawinfo for the G3X LRUs, use this information when determining power supply requirements. All installedelectrical appliances must be considered when determining total power requirements.2.2.1.1 GAP 26 Power RequirementsThe 010-01074-00 version of the GAP 26 does not require power as it does not have a heater. The initialcurrent vs temperature requirements for the 010-01074-10 and 010-01074-20 are listed in Table 2-1. SeeSection 5.5.2 for acceptable wiring configurations.CAUTIONDo not connect the heated/regulated version of the GAP 26 (010-01074-20) to 28 VDC.The heated/non-regulated version of the GAP 26 (010-01074-10) may be connected toeither 14V or 28V. See Section 5 for wiring information.Table 2-1 GAP 26 Initial Current Draw vs Probe Temperature (-10, -20 units only)Probe Temperature -40°C (-40°F) 0°C (32°F) 50°C (122°F) 100°C (212°F) 175°C (347°F)Amps 12 Amp 9.25 Amp 7.3 Amp 5.85 Amp 4.36 AmpTable 2-1 refers to probe temperature at initial turn-on. For example, upon turn-on at -40°C, the standard(-10) or regulated (-20) heated probes will initially draw 12 amps, but will draw less current as they warmup.The -10 non-regulated probe draws current proportional to the probe temperature as shown in Table 2-1.The -20 heated regulated probe uses similar power to the -10 probe when airborne, but will limit thecurrent to regulate the probe temperature to ~75°C (167°F) when the probe temperature reaches thisvalue.
