Electrical installation and wiring
4-10 Chapter 4: Installation 98-158751-C
4.3.4 To wire the MCHPA with AC input
ARINC-781 compliant.
The aircraft power bus provides the electric power required to operate the MCHPA, and a
chassis connection to the aircraft chassis and the installation tray. The +115 VAC power
wire must include a circuit breaker capable of carrying the required current continuously
under the required environmental conditions.
The following drawing shows the wiring of the MCHPA AC power supply.
The COLD does not need to go through a breaker.
The COLD must not be connected to chassis ground. Connect the COLD to the aircraft
power bus as stated in the following table.
Pins for AC power
The following list shows the pins used for the AC power supply.
Figure 4-4: Wiring AC power
CSDU
pin
Name Description
BP1 +115 VAC Line (Hot) +115 VAC Line (Hot) power input from aircraft
power bus.
BP7 +115 VAC Neutral
(Cold)
+115 VAC Neutral (Cold) return from aircraft
power bus.
BP8 Chassis Ground Chassis connection, connect to the installation
tray and Aircraft chassis.
Table 4-3: MCHPA pins (AC input)
MCHPA
BP7 +115 VAC Neutral (Cold)
Aircraft power Bus
115 VAC
(360 Hz to 800 Hz)
[1] + [2] Total resistance (Hot and cold) max. 1 Ohm incl. circuit breaker.
[3] Directly to installation tray and aircraft chassis, max. 25 mOhm resistance.
[4] Compatible with an aircraft circuit breaker of the following characteristics: 115VAC /
5A Solid state power controllers (SSPC)
BP8
BP1 +115 VAC Line (Hot)
Chassis
[4]
5 A
[1]
[3]
[2]
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