Restrictions On Inrush Current For On/Off Operation - Omron NX Series Hardware User Manual

4 Designing the Power Supply System
4-3-4

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 4-24 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.
2
Irms= Ip × D+Ia
(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
0A
τ
4-20
2
× (1-D)
T
Irms
NX-series NX102 CPU Unit Hardware User's Manual (W593)