ISO 27027:2014

INTERNATIONAL ISO
STANDARD 27027
Second edition
2014-10-15
Aerospace — Solid-state remote
power controllers — General
performance requirements
Aéronautique et espace — Contacteurs-disjoncteurs statiques
commandés à distance — Exigences générales de performance
Reference number
ISO 27027:2014(E)
©
ISO 2014

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ISO 27027:2014(E)

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ISO 27027:2014(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Requirements . 4
4.1 Detail requirements . 4
4.2 Electrical characteristics . 4
4.3 Performance . 4
5 Quality assurance provisions . 6
5.1 Electrical characteristics . 6
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ISO 27027:2014(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
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For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 1, Aerospace electrical requirements.
This second edition cancels and replaces the first edition (ISO 27027:2008), which has been
technically revised.
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ISO 27027:2014(E)

Introduction
This International Standard is the general performance requirements of the solid state (remote) power
controller (SSPC) for aerospace.
Trend of aircrafts electric power system will be toward high voltage system. To accompany that trend,
arc fault in the aircraft’s wiring will become one of the major problems for the electric power distribution
system. This second edition takes into account the arc fault detection.
The purpose of this International Standard, the definitions of SSPC and the contents of the document
are as follows:
a) The purpose of this International Standard
1) To standardize the requirements for SSPC those are physically and environmentally diversified.
2) To provide the applicable standard document for various SSPC.
b) The definitions of SSPC
1) Consists of a solid-state switching device and its driver circuit.
2) Turns on/off the power output by receiving the control signal.
3) Detects the over current in the load which results in limiting this current or shutting down
for this current and/or optionally detects the arc fault in the circuit which results in shutting
down the fault.
4) Indicates the on/off status of the power output.
c) The contents of this International Standard
1) Definitions of the technical term.
2) Electrical requirements.
3) Test methods.
In order to satisfy the purpose of this International Standard, requirements such as physical,
environmental, and individual items are specified in accordance with the detail requirements that are
issued individually.
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INTERNATIONAL STANDARD ISO 27027:2014(E)
Aerospace — Solid-state remote power controllers —
General performance requirements
1 Scope
This International Standard specifies the definitions, titles of general performance requirements, and
test methods to determine the performance of solid state (remote) power controller (SSPC) for use in
aerospace electrical power systems.
The SSPC consists of solid state-switching device(s) and associated solid-state circuitry for protection,
action of control signals, and providing status information.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 1540, Aerospace — Characteristics of aircraft electrical systems
ISO 7137, Aircraft — Environmental conditions and test procedures for airborne equipment
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
arc fault
sustained luminous discharge of electricity across a gap in a circuit or between conductors
Note 1 to entry: Arc impedance can reduce low-voltage fault current magnitudes appreciably.
3.2
current limiting
function to limit the power output current to the required level within required time from overload or
short circuit conditions which is shown in Figure 2
3.3
load voltage
voltage between the power output terminal of the SSPC and the power ground
3.4
load voltage rise and fall time (D.C. devices and non-zero crossing turn-off A.C. devices)
time interval between 10 % and 90 % of the steady state load voltage value which is shown in Figure 1
a) for D.C. devices
3.5
off state
condition which, with the turn-off signal applied, the device prevents power from being passed to the load
3.6
on state
condition which, with the turn-on signal applied, the device allows power to be passed to the load
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ISO 27027:2014(E)

3.7
parallel arc fault
arc fault condition in which arcing occurs in a circuit from line-to-line or line-to-ground and not
through any load(s)
Note 1 to entry: Only the arc impedance and the system current impedance limit the magnitude of the arc fault current.
3.8
peak let-through current
peak value of the current at maximum system voltage that the SSPC will conduct for a specified time
interval without damage
3.9
power dissipation
power dissipation which includes all power dissipated in the power switching circuit, power losses due
to internal leakage currents, and power supplies
Note 1 to entry: When SSPC is OFF, the power dissipation includes only dissipation due to leakage currents and
internal power supplies.
3.10
reset
restoration of the tripped SSPC to a state from which it can be turned ON
3.11
reverse current
current into the load terminal of the SSPC from the load energy source
3.12
series arc fault
arc fault condition in which the current passes through the arc and each circuit load
Note 1 to entry: The load equipment limits the magnitude of the arc fault current.
3.13
short circuit
circuit with the impedance of less then 1 mΩ applied between the output terminal and ground
3.14
soft on/off
function for the power output current to increase linearly with turn-on signal and to decrease linearly
with turn-off signal
3.15
supply voltage
voltage applied between the power input terminal of the SSPC and the power ground
3.16
trip
automatic reversion to the OFF state of the SSPC output caused by an overload condition or detection of
arc fault
3.17
trip curve
curve which sets the minimum and maximum trip points of the SSPC and is plotted as current verses time
3.18
trip free
feature which will prevent subsequent re-closing unless preceded by a reset signal, when the SSPC has
tripped due to an overcurrent condition or detection of arc fault
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ISO 27027:2014(E)

3.19
trip time
time interval between the application of an overcurrent condition or detection of arc fault and the 10 %
value of rated output current
Note 1 to entry: In general, the higher the overcurrent condition, the shorter is the trip time.
3.20
turn-off signal
control signal level at which the power controller is turned OFF
3.21
turn-on signal
control signal level at which the power controller is turned ON
3.22
turn-off time
A.C. devices with zero-crossing turn-off
time interval between initiation of turn-off signal and the time when the output switch is OFF at zero crossing
Note 1 to entry: Shown in Figure 1 b).
3.23
turn-off time
D.C. devices and non-zero crossing turn-off A.C. devices
time interval between initiation of turn-off signal and the time when the output reach 10 % of its steady-
state ON value
Note 1 to entry: Shown in Figure 1 a).
3.24
turn-on time
A.C. devices with zero-crossing turn-on
time interval between initiation of turn-on signal and the time when the output switch is ON at zero crossing
Note 1 to entry: Shown in Figure 1 b).
3.25
turn-on time
D.C. devices and non-zero crossing turn-on A.C. devices
time interval between initiation of turn-on signal and the time when the output reach 90 % of its steady-
state ON value
Note 1 to entry: Shown in Figure 1 a).
3.26
unwanted trip
tripping function in response to a condition that is not an arcing fault but a condition that occurs as part
of the normal or anticipated operation of circuit components
Note 1 to entry: Nuisance trip is synonymous with unwanted trip.
3.27
voltage drop
voltage across load and line terminals of the SSPC in the ON state at the specified load
3.28
zero voltage turn-on/zero current turn-off (A.C. devices only)
characteristic that requires the SSPC to turn ON and turn OFF only at the half-cycle zero-crossing point,
regardless of when the control signal is applied or removed
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ISO 27027:2014(E)

4 Requirements
4.1 Detail requirements
The individual item requirements shall be specified in accordance with the detail requirements that are
issued individually. It is recommended to use ISO 7137 for the specification of environmental conditions
and test procedures for the SSPCs installed in the airborne equipment.
4.2 Electrical characteristics
When tested as specified in 5.1, the SSPC shall operate with supply voltage variations in accordance
with ISO 1540 or the detail requirements, and the SSPC shall be capable of controlling all type of loads
as required by the detail requirements.
4.3 Performance
4.3.1 Control signals
When tested as specified in 5.1.2, the control signals shall be as specified in the detail requirements.
4.3.2 Turn-on and turn-off time
When tested as specified in 5.1.3, the turn-on and turn-off time shall be as specified in the detail
requirements.
4.3.3 Load voltage rise and fall time (soft on/off function)
When tested as specified in 5.1.4, the rise and fall time as the soft on/off function shall be as specified
in the detail requirements.
4.3.4 Isolation
The control/power isolation test voltage shall be as specified in the detail requirements, when tested as
specified in 5.1.5.
4.3.5 Control signal levels
When tested as specified in 5.1.6, the control signal levels shall be as specified (see 4.1). Where maximum
control signals are specified (see 4.1) the signal shall be applied for 10 min without any damage to the SSPC.
4.3.6 Voltage drop
When tested as specified in 5.1.7, the voltage drop shall not exceed the values specified in the detail
requirements for load current values from no load to 100 % rated.
4.3.7 Off-state leakage current
When tested as specified in 5.1.8, the leakage current shall not exceed the values specified in the detail
requirements.
4.3.8 Off-state output voltage
When tested as specified in 5.1.9, the output voltage shall not exceed the values specified in the detail
requirements.
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ISO 27027:2014(E)

4.3.9 Power dissipation
When tested as specified in 5.1.10, the power dissipation shall not exceed the values specified in the
detail requirements.
4.3.10 Overload characteristics
4.3.10.1 Current limiting
When specified in the detail requirements and tested as specified in 5.1.11.1, the output current shall be
within the trip curve specified. At the initiation of the overload condition, the peak let through current
(see 4.1) shall not exceed the value specified.
4.3.10.2 Trip characteristics with the overload condition
When tested as specified in 5.1.11.2, the SSPC shall not reset until commanded, the trip time shall be
within the trip curve specified in the detail requirements without any damage.
4.3.11 State indication
The SSPC shall provide the means of state indication specified in the detail requirements when tested as
specified in 5.1.12. State indication
...