Specifications

EMC-CS-2009.1
© Copyright Ford Motor Company – All Rights Reserved Page 114 of 121
February 11, 2010
Annex G (Normative): Load Simulator Requirements
The Load Simulator is a shielded enclosure that contains all external electrical interfaces (sensors, loads etc.) normally
connected to the DUT. The Load Simulator also serves as an RF boundary for the DUT cable harness in addition to serving
as an interface to support and monitoring equipment required during testing.
A typical Load Simulator is illustrated in Figure G-1. The circuits shown serve as examples of what can be contained within
the Load Simulator. Actual circuit content is specific to the DUT's functionality. However, the following requirements shall
be followed when designing the Load Simulator.
 All interface circuits within the Load Simulator except CAN shall include a capacitance of 10 nF located
between each interface circuit and the Load Simulator chassis unless actual electrical loads are used. Omission of
the 10 nF capacitor shall require approved from the FMC EMC department prior to commencement of testing..
The
10 nF capacitance value represents the interface capacitance for most modules.
If the Load Simulator contains a
CAN interface (includes MS or HS CAN), the capacitance shall be 470 pf.
The capacitors shall be package as
close as possible to the Load Simulator/DUT harness interface connector. Figure G-1 illustrates location of these
capacitors.
It is recommended to use surface mount capacitors on a separate PCB mounted directly to the interface
connectors. This minimizes lead inductance between the interface circuit and Load Simulator chassis. Filter pin
connectors may be use, but only with prior approval of the FMC EMC department.
 If the DUT contains CAN communications, the circuits illustrated in Figure G-2 shall be located within the Load
Simulator. Configuration A shall be used for devices that contain internal CAN bus termination. Configuration B
shall be used for devices that contain no termination.
 Production intent components shall be used for the loads wherever possible. This is particularly critical for
inductive and pulse width modulated (PWM) circuits. If actual loads are not available, simulated loads may be used,
but shall accurately represent the impedance (resistance, capacitance and inductance) that is expected in a
production vehicle.
Simple resistive loads shall not be used unless approved by the FMC EMC department

If the DUT is powered from another electronic module (e.g. sensors), the module’s power supply shall be accurately
simulated from within the Load Simulator. Other active devices may be contained within the Load Simulator, but
appropriate steps shall be taken to prevent potential influences of RF energy on device operation.
 In general, all inputs and outputs shall be referenced to power ground established at one point within the Load
Simulator and connected to the Load Simulator metal chassis. The only exception to this for CI 250, where it is
required to introduce a voltage offset between the ground plane and the loads contained in the Load Simulator. See
Section 18-2 for additional detail.
Figure G-3 illustrates the Load Simulator in a typical test setup.
 The Load Simulator chassis shall be electrically bonded to the test setup ground plane via direct connections
(screws) and/or ground straps. Alternative bonding methods (e.g. copper tape with conductive adhesive) is not
permitted.
 DUT inputs requiring external signal sources are facilitated via the Load Simulator. Although fiber optic media is
recommended for these connections, coaxial cables may be use to connect remote support equipment to the Load
Simulator. However, if coaxial connections are used, all cabling shall be have ferrite beads installed on the cable at
intervals not exceeding 150 mm. Use of ferrite beads other than the type delineated in Figure G-3 shall be reviewed
and approved by the FMC EMC department as part of the laboratory recognition process (see
http://www.fordemc.com).
 Fiber optic media shall be used to connect DUT outputs to remotely located monitoring equipment. The frequency
bandwidth of the fiber optic media shall be selected to be compatible with the operating bandwidth of the monitored
DUT signal, but limited to avoid unintentional RF energy from coupling to, and potentially affecting the test
monitoring instrumentation. Use of non-optical interfaces to monitoring equipment is permitted only with prior
approval by the FMC EMC department. Details concerning signal monitoring and support equipment interface shall
be documented in the EMC test plan
 All fiber optic media shall require prior verification to be immune to the RF stress levels delineated in section 11 of
this specification.
 Wires connecting the battery to the Artificial Networks and Load Simulator shall have ferrite beads installed on the
cable at intervals exceeding 150 mm.