ISO 1540:2006 specifies the characteristics of electrical power supplied to the terminals of electrical utilization equipment installed in an aircraft. It is intended to support the interface definition for user equipment designed to accept electrical power on a variety of new civil aircraft applications, such as those certified via the Technical Standard Order (TSO) certification process. It might not be desirable for equipment targeted to a single application or specific military application to follow ISO 1540:2006 because of the penalties associated with multi-application.

ISO 1540:2006 also attempts to provide background to the development of these requirements that may be useful to those designing and/or integrating modern aircraft electrical systems. The delivered quality of this electrical power is a result of the combined characteristics of the electrical power source, distribution and user equipment. While only user equipment restrictions are specifically defined, background to key source and distribution equipment interfaces are identified in order to support development of the overall system.

A wide variety of electrical supply types and distribution parameters have been considered, as may be found on both small and large transport aircraft. Sources considered include physically rotating and static types, provided either on-aircraft, or as part of the ground support equipment. Distribution voltages addressed are

• nominal 14 V, 28 V and 42 V d.c.;
• nominal 26 V a.c., 400 Hz, one-phase;
• nominal 115/200 V rms and 230/400 V rms a.c., both one-phase and three-phase, at either a nominal 400 Hz constant frequency (CF), or over a variable frequency (VF) range which includes 400 Hz.