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6.8 ANALOGUE OR MODBUS INPUT FOR SHAFT GENERATOR
The PEM4 + SPU3 system is able to calculate the total power generated by the main engine(s) when
shaft generators are incorporated in the vessel’s propulsion system. When the generators are positioned
at the propeller shaft line (inline or tunnel gear type) or connected to the gearbox as a Power Take Off
(PTO) the PEM4 + SPU3 system can add up both propulsion power and the measured generator power
in order to calculate the correct SFOC values per engine.
Please be aware that the efficiency of the generators themselves is decreasing the overall
SFOC value by a certain percentage.
A maximum of 2 input signals (4
–20mA or Modbus) can be connected to the SPU3 representing the shaft
generator power level(s).
Analog input
Signal
Type
of
input
signal
Terminal
number
on
SPU3
Backplane-
‘X’
Shaft generator one
4
–20mA - active
Terminal nr. X1 and X2
Shaft generators two
4
–20mA - active
Terminal nr. X1 and X2 + X3 and X4
Shaft generator one
4
–20mA - passive
Terminal nr. X5 and X6
The number of Backplane-
“X” might differ per PEM4 configuration, depending on the total
system. Please refer to the connection diagram what comes with the project.
Modbus input
Signal
Type
of
input
signal
Terminal number on SPU3
Shaft generator one
Modbus
Terminal nr. J1 (see section 6.12)
Shaft generators two
Modbus
Terminal nr. J2 (see section 6.12)
Make sure that the shaft generator settings in the PEM4 + SPU3 system itself are set correctly. You are
able to adjust these shaft generator settings in the PEM4 Settings menu (
advanced user only)
.
When 2 passive shaft generator outputs have to be connected to the PEM4 + SPU3 system please
contact VAF Instruments.
