Omron NX1P2 series, Hardware User Manual

Page: 137 / 264

4-3-5
Restrictions on Inrush Current for ON/OFF Operation
This section describes the restrictions on inrush current from the I/O power supply that occurs when
connected external devices turn ON and OFF.
Inrush Current Restrictions
If inrush current to the I/O power supply occurs when a connected external device turns ON or OFF,
do not allow the effective value of the I/O power supply current to exceed the following rated values
when the inrush current is added to the current consumption from the I/O power supply.
• Maximum I/O power supply current
• Current capacity of power supply terminals for the I/O power supply
Also, maintain the peak inrush current 20 A maximum and maintain the pulse width 1 s maximum.
Refer to
4-4-3 Selecting Protective Devices on page 4-25 for the rated values of the items when the
CPU Rack is used.
Calculating the Effective Value of the I/O Power Supply Current
The formula to calculate the effective value of the I/O power supply current, Irms, is given below.
Irms= Ip
2
× D+Ia
2
× (1-D)
(D=
τ
/T)
• Ip: Peak inrush current (A)
• Irms: Effective value of I/O power supply current (A)
• Ia: Total current consumption from the I/O power supply (A)
• D: Inrush current duty
•
t
: Inrush current pulse width (s)
• T: Inrush current period (s)
Ip
Ia
Irms
τ
T
0A
4 Designing the Power Supply System
4-21
NX-series NX1P2 CPU Unit Hardware User’s Manual (W578)
4-3 Designing the I/O Power Supply System
4
4-3-5
Restrictions on Inrush Current for ON/OFF Operation