Technical information

CONTROL CIRCUITS

In the absence of the over-temperature test the component can be used, but

the output current must be downgraded to 50% (that is to say a 10 A power

unit should be limited with a special 5 A protection).

The protection of the power units should be done in accordance to the

indications given in the instructions, making sure however that the

components envisaged are suitable at the point of installation in accordance

with CEC or NEC (see the overcurrent protection).

Note: All the Rockwell Automation power supplies in the 1606-XL

Family are certified for industrial environments and are not

subject to downgrading or to limitations!

b) Transformers / autotransformers: the general Class 1 control circuit does

not require the separation between the windings (as already mentioned, only

NFPA79 for Industrial Machinery imposes the use of the transformer).

The protection of the transformers and autotransformers should follow the

rules given in the specific section.

1.6 Control Circuit Class 2

The main advantage of Class 2 circuit is the possibility given by UL508A to use

non-approved components:

this is however only applicable to internal conductors

and control circuit components.

This is very often the only way out allowed to those using components, for

example electronic cards, customised or own products, that could be challenged

by the AHJs.Alternatively these components would need to be approved; such

thing requires time and a non-justifiable expenditure.