ES4440.2 Compact Failure Simulation Module - User’s Guide 27
ETAS Hardware Features
2.7 Safety Concept
The ES4440.2 Compact Failure Simulation Module has protective mechanisms
against overtemperature and overcurrents.
2.7.1 Resetting on Overtemperature
2.7.2 Protecting the Rails/Relays
To protect the relays and the entire circuit, the ES4440.2 Compact Failure Simu-
lation Module has five fuses. These are standard blade fuses used commonly in
the automotive environment.
The 80 V channels are intended for injector or ignition signals. These signals are
pulsed direct voltages with a pulse width of just a few milliseconds and with
voltage peaks of up to 250 V. As the root mean square values of the voltages are
under 80 V, a 10 A/80 V fuse can be used.
2.7.3 Automatic Monitoring of the Fuses
The state of the fuses can be monitored by an automatic application on the host
system. The information is transferred via Ethernet or CAN (command: test
fuses())
This kind of automated monitoring takes place as follows:
1. Checking the state of the fuses
2. Applying an failure
3. Resetting the failure
4. Checking the state of the fuses
When in operation, the temperature of the ES4440.2 Compact Failure Simula-
tion Module is monitored at various points in the housing. If an overtempera-
ture is detected at any one of these points, a reset is executed which is
indicated via the yellow ”Reset” LED on the front panel (see Fig. 2-4
on page 24).
All relays are reset during a reset, i.e. all failures set are canceled. Set failures
are not executed and acknowledged with an failure message as long as the
overtemperature condition applies.
When software monitoring of the temperature fails, the internal power supply
and all LEDs are powered off. If the temperature falls back under the threshold,
the device is powered on again and a reset executed.
Fuse* Function Specification
E1 Protects rail 2 against ±UBatt_B 20 A/32 V
E2 Protects rail 1 against rail 2 20 A/32 V
E3 Protects rail 1 against ±UBatt_A 20 A/32 V
E4 Protects the resistor cascade 3A/32V
E5 Protects the 80 V rail 10 A/80 V
* For details on the position of the fuses, please refer to the figure in the sec-
tion "To change fuses" on page 29.
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