Power Supply and Power Distribution Requirements
The power supplies and power distribution, if incorrectly designed, are a possible electrical or fire safety hazard and can contribute to common cause failure. It is therefore necessary to:
• Establish the power philosophy, specific earthing philosophy, power requirements, and the separation requirements where items of equipment are separately supplied, for example system internal supplies and field loop supplies.
• Make sure that the chosen Power Supply Units (PSUs) are compatible with the powerfeeds supplied. Alternatively, measures must be put in place to make sure that the power feeds stay within the specifications of the PSUs.
• Define the power distribution requirements, together with the protective philosophy for each distribution; for example, current limited at source or protective devices. Where protective devices are used, it is important to find out that sufficient current will be available to make sure their protective action and the protective device can break the maximum prospective fault current.
• Make sure that the power supplies are sufficient to meet the system load and for any foreseeable load requirements and load transients
• Make sure that the power supplies have a minimum hold up time of 10 ms.
• Make sure that the power distribution cabling is sized to allow the maximum prospective fault currents and tolerable voltage losses. This is specifically important where floating supplies are employed and other power sources can cause high prospective fault currents if multiple earth faults occur.
Controller Power Supply Requirements
A controller requires the following power supply sources:
• A dual redundant power supply of + 24 Vdc with an operating range of 18 Vdc to 32 Vdc. The AADvance controller is designed to accept supply transient and interference according to IEC 61131 part 2.
An over current fault in the controller must not cause the system to lose power. Consequently, the power sources must be able to supply the peak current to open any over current protection devices (such as fuses) without failing.
The power supply protection of the controlleris in the modules, the power distribution arrangement must have a circuit breaker on the input side of each power source. The controller is designed to be resistant to a reverse polarity connection without permanent damage.
The power sources must come from a commercially available industrial uninterruptible power supply (UPS) system. An applicable UPS must have the capacity sufficient to satisfy the entire system load (including field devices and the controller) and an applicable contingency allowance for projected future expansion.
Power Arrangements for Field Devices
Output modules use an external source of power for field devices. This may be the power source used forthe controller or a separate power source.
• For digital and analogue outputs a field power supply of +24 Vdc within a range of 18-32 Vdc is required.
Recommended field circuits are given for each type of I/O module later in the section “Connecting Field Wiring”.
Power Distribution Protection
The power distribution circuit for each field input and for each output module must be protected, externally to the controller. Rockwell Automation recommend that power distribution must meet national and local panel wiring protection standards.
Digital Output Field Power
Special fusing arrangements are required for Digital Output field supplies for UL, ATEX and IECEx approved installations, (see topic on field loops for Digital Output Modules).
Estimating Power Consumption
To estimate the power supply requirements (power supply sizing) you need to know the power consumption of all the modules. Use the following table to estimate the system power consumption.
Related recommendations:
FOXBORO FBM216 BP0927AJ
A-B 800F-AEAU2CG148800F
Allen-Bradley 1756-CN2
A-B 889D-F4NEDM-2889
Rockwell A-B 5069-OBV8SCompact5000
EMERSON 9191-FP
Rockwell Automation 442G-MABLB-UL-P49PTL
Schneider X80-D BMEXBP0400 4
Allen Bradley A-B 1489-A3D250RUL489 BIEC60947-2
ABB IRB 6650S, 3HAC038800-001 Axis 1-6
GE IC610MDL125B
ABB DSQC431 3HAC036260-001
Rockwell Automation 9527-I5PRL128-1KMISaGRAF5
Fireye 65UV5-1004EC UV
FOXBORO A2050UZ
ABB DCS401.0230
ANSALDO 211QS50003B
ABB UA D206 A101 3BHE019958R0101
GE IC693CHS398
More…


