Electromagnetic compatibility
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Read this manual carefully before starting any work!
This is particularly applicable to the chapter “General Safety Instructions”
and the respective safety instructions in the chapters.
4 Electromagnetic compatibility (EMC)
The system manufacturer must perform their own EMC measurement of the entire system in order to
ensure the trouble-free operation of the electrical and electronic systems.
- Only a lead-acid battery is permissible for the engine control unit supply -
Other system-side consumers on this battery must be coordinated with MAN.
Unfavorable customer-side wiring can result in a harmonics component in the supply voltage of the engine
control unit becoming too high. The capacitors in the control unit are then exposed to an excessively high
load, which decreases the service life of the control unit.
The harmonics in the supply voltage on the engine control unit must be measured; this is part of the
installation acceptance.
Conditions for this:
S Engine at idle
S Electric load of the engine's own alternator
S Measurement input at engine ground connector
S Measurement input at terminal 30 of the engine control unit
S Measurement of effective value with an AC voltmeter
The system-side wiring must be changed if the AC component exceeds 400 mV (RMS-capable digital
multimeter with 20 Hz – 100 kHz measurement bandwidth).
To permit malfunction-free operation of the electronic control of the engine and the aftertreatment system,
it is mandatory that the MAN overall system is protected from external effects via the voltage supply
(overvoltage, rapid transients, conducted high frequency)!
This is effected via overvoltage protection components included upstream of the voltage supply connection
of the MAN overall system to the battery, i.e. terminal 30, terminal 31 and terminal 15 (before the pick-up of
terminal 15 from terminal 30). This ensures that terminal 15 is also protected from interference.
The cables for terminal 30, terminal 31 and terminal 15 are to be twisted and shielded directly after the
overvoltage protection component. The lay length is (40...60) mm or (25...17) twists per meter, depending
on the cross-section of the cable (1...2.5) mm².
The shielding must always be applied on both sides on functional ground FE!
If the cable exceeds a length of 10 m, in each case the shielding is to be additionally applied on functional
ground FE every 10 m!
Overvoltage protection components:
S Optionally electric voltage filter MAN item number 51.25907-0027 (suitable for 10 A at 80 °C)
or
S Suppressor diode triple (Transient Voltage Suppressor TVS) of 3 x 5KP36CA from Littlefuse at MAN
available in the form of overvoltage protection module 51.25902-0143
EMC-robust rail pressure sensor with 2-terminal applications (e.g. rail applications):
To attain voltage resistance of approx. 70 V with respect to the housing (ground) and battery negative,
rail pressure sensor 51.27421-0178 is to be used!
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