Omron CRT1 - 10-2008 Operation Manual page 108

Power Supply Wiring
Allowable Currents for
Cables
Allowable Currents for
Connectors
Voltage Drop
Cable Voltage Drop
Flat Connector Plug: 5 A max. (UL: 4 A)
Flat Connector Socket: 5 A max. (UL: 4A)
Cable
Master
Unit
(a)
Power
supply, Slave Unit
24 VDC current con-
sumption I
The allowable currents for cables and connectors are given below.
Select the communications cable so that the total current consumption of all
Slave Units does not exceed the allowable current of the cable.
Cable allowable current ≥ I
(For the allowable cable current for "a" in the above diagram)
There are limits to the allowable current for the communications power supply
connectors on the Master Unit and Repeater Units, Flat Connector Sockets,
and Flat Connector Plugs. Do not allow the current flow where these connec-
tors are used to exceed the allowable current.
Communications power supply connectors on CS/
CJ-Master Units
Communications power supply connector on
Repeater Unit
Flat Connector Sockets
Flat Connector Plugs
Multidrop Connector
The voltage drop must be considered so that the power supply voltage at the
Slave Unit that is the farthest from the power supply will still be within the
allowable power supply range.
The voltage drop is expressed by the following formula.
Voltage drop (V) = Current (A) × Cable conductor resistance (Ω/m) × Cable length
(m) × 2
If the voltage drop is too large and power cannot be supplied to the farthest
Slave Unit within the allowable range, add a Repeater Unit and supply power
from the Repeater Unit.
Slave Unit Slave Unit
current con- current con-
sumption I sumption I
2
1
+ I + I + · · · · I
1 2 3 n
Name
Section 3-5
Terminating
Resistor
Slave Unit
current con-
sumption I
n
3
Model Allowable
current
CS1W-CRM21 5 A
(UL: 4 A)
CJ1W-CRM21
CRS1-RPT01
DCN4-TR4
DCN5-TR4
DCN4-BR4
DCN5-BR4
DCN4-MD4
85