At a Glance
The different choices of power supply for sensors and pre-actuators linked to discrete input/output modules require certain usage precautions to be observed.
External Direct Current Power Supplies
| WARNING | |
|---|---|
UNEXPECTED EQUIPMENT OPERATION When using an external 24 VDC direct current power supply,
use either: regulated power supplies or non-regulated power supplies with:
Rectified power supplies with no filtering are prohibited. Failure to follow these instructions can result in death, serious injury, or equipment damage. | |
Ni-Cad Battery Power Supplies
Ni-Cad battery power supplies can be used to power sensors and pre-actuators and all associated inputs/outputs that have a normal operating voltage of 30 VDC maximum.
While being charged, this type of battery can reach, for a duration of one hour, a voltage of 34 VDC. For this reason, all input/output modules with an operating voltage of 24 VDC can withstand this voltage (34 VDC) for up to one hour every 24 hours. This type of operation entails the following restrictions:
at 34 VDC, the maximum current withstood by the outputs must under no circumstances exceed the maximum current defined for a voltage of 30 VDC
temperature downgrading imposes the following restrictions:
80% of inputs/outputs at 1 up to 30°C
50% of inputs/outputs at 1 up to 60°C
| CAUTION | |
|---|---|
OVERHEATING HAZARD Take into account the temperature derating of the discrete
I/O modules at the installation to prevent the device from overheating
and/or deteriorating. Failure to follow these instructions can result in injury or equipment damage. | |
External AC Current Power Supplies
All BMXDAI••••, BMXDAO••••, BMXDRA••••, and BMXDRC•••• modules are designed for a use in zone A and B defined in the PLC standard IEC 61131-2 and the generic EMC standard IEC 61000-6-2 without any specific protection against surges.
The following figure shows the zones defined in the PLC standard IEC 61131-2:
Zone A Local power distribution
Zone B Dedicated power distribution
Zone C Factory mains
1 Protection network should be appropriate to reduce Severity Levels from those of outdoor to Zone B.
2 Protection network should be appropriate to reduce Severity Levels from those of Zone A to Zone B
It is also suited to be installed in a power generation station/substation according to the generic standard IEC 61000-6-5 for interfaces type 1 and 2, without any specific protection against surges.
The following figure shows the interface types defined in the generic standard IEC 61000-6-5:
1 Inside protected area
2 Inside interface and/or control room and/or process area not involved in the electrical process
3 Inside or from process area involved in the electrical process
4 Connections from outside (HV area and external telecommunication)
Protection Against Surges of AC Power Lines for More Severe Environments
The design of these modules are suited to ensure an immunity level for surges of 2 kV Line to ground and 1 kV line to line and do not require any external protection on AC line branch.
If it is intended to install the PLC and its AC I/Os in a IEC 61131-2 zone C or to a IEC 61000-6-5 type 3 or type 4 interface: primary protection provided only and severe interference coupling, it is the responsibility of the system integrator or the customer to take care of the system and protect it in the right manner.
It is possible, providing mitigation measures, to install the PLC and the IO module in a such environment.
All the installation requirements are detailed in the chapter J - Overvoltage protection of the Schneider Electrical Installation Guide. This documentation is available for download on www.se.com.
Adding a type 2/class II surge protection device (SPD), for example an iQuick PRD20r modular surge arrester with voltage protection level (Up) ≤1.5 kV, will allow to withstand surges of 4 kV Line to ground and 2 kV line to line.