Ngày đăng: 06:56:36 06-01-2015
The power consumption of a complete station consists of the sum of all individual consumptions.
An AC500 CPU cluster has
a power consumption of the CPU itself over the terminals L+ and M of the Terminal Base. After conversion of the voltage, also the I/O-Bus for the attached I/O modules is supplied then.
a power consumption over the process supply voltage terminals ZP and UP of the Terminal Units / the L+/M or UP/ZP terminals of the eCo I/O Modules. Through this the digital and analog outputs are also supplied.
The two supply voltages can be provided by the same power supply unit. The CPU and the I/O modules should, however, be fused separately. Of course also separate power supplies are possible. See the previous chapters regarding equipotential bonding and cable routing.
In the following example, the AC500 control system consists of
- the CPU PM581-ETH
- the 4 communication modules CM572-DP (1x), CM575-DN (1x), CM577-ETH (1x), CM578-CN (1x)
- the 7 expansion modules DC522 (1x), DC523 (1x), DC532 (1x), AX521 (1x), AX522 (1x), AI523 (1x), AO523 (1x)
- as well as the required Terminal Bases and Terminal Units
Remark: Because of the high total current consumption of the digital I/O modules (from UP = 24 DC), the supply is divided up into several electric circuits fused separately. The maximum permitted total current over the supply terminals of the I/O Terminal Units is 8 A.
The total current can be calculated as follows:
ITotal = ICLUSTER + IUP
with the following assumptions
ICLUSTER = ICPU + II/O-Bus + IC1 + IC2 + IC3 + IC4 (CPU + communication modules + I/O-Bus)
II/O-Bus = Number of expansion modules x Current consumption through the I/O-Bus per module
and
IUP = IUP1 + ILOAD1 + IUP2 + ILOAD2 + IUP3 + ILOAD3 + IUP4 + ILOAD4 + IUP5 + ILOAD5 + IUP6 + ILOAD6 + IUP7 + ILOAD7
If one assumes that all outputs are switched on and are operated with their maximum permitted load currents (under compliance with the maximum permitted currents at the supply terminals), then the following values are the result for the example shown above:
To be able to select the fuses for the station correctly, both the current consumption and the inrush currents (melting integral for the series-connected fuse) must be taken into consideration.