Siemens SINUMERIK ONE NCU 1750 Equipment Manual page 117

Requirements placed on the DC power supply
Inadequately fused supply cables can be life-threatening
In the case of supply lines > 10 m, protectors must be installed at the device input in order to
protect against lightning (surge).
The DC power supply must be connected to the ground/shield of the I/O module for EMC and/
or functional reasons. For EMC reasons, this connection should only be made at one point; see
also EMC Installation Guide.
Table 12-13
Rated voltage
Non-periodic overvoltages
Transient voltage interrup‐
tions
Digital inputs
The 24 V supplied at X1 are used to supply the 72 digital inputs.
If the internal supply voltage is not used to supply the digital inputs, this can optionally be
replaced by an external power supply (24 VDC). The reference ground of the power supply
source must each be connected with X111, X222, X333, pin 1 (GND). X111, X222, X333, pin 2
(P24OUT) then remains open.
Digital outputs
To supply (24 V DC) the digital outputs, an additional external power supply source is required.
The power supply is connected to terminals X111, X222 and X333 via pins 47, 48, 49 and 50
(DOCOMx). Ground pins must be connected to a common chassis ground.
NCU 1750
Equipment Manual, 01/2022, A5E45627807B AE
WARNING
Requirements of the DC power supply
According to EN 61131-2
Voltage range (average value)
Voltage range (dynamic)
Voltage ripple peak-to-peak
Ramp-up time at POWER ON
Duration of overvoltage
Recovery time
Events per hour
Outage time
Recovery time
Events per hour
Connectable components
12.2 PP 72/48D PN
24 VDC
20.4 VDC to 28.8 VDC
18.5 to 30.2 VDC
5% (unfiltered 6-pulse rectifi‐
cation)
Any
≤ 35 V
≤ 500 ms
≥ 50 s
≤ 10
≤ 3 ms
≥ 10 s
≤ 10
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