Beijer-electronics iX T12C EN Manual de usuario descargar pdf (Pagina 30)

Additional Installation Tips

7.5 Safety

Most of the operator panels are fed with 24 V DC.

Power supply

230 V AC to 24 V DC

Power supply

230 V AC to 24 V DC

Power supply

230 V AC to 24 V DC

Operator panel

Distance?

Small controller with expansion unit

+24 V

0 V

230 V AC

COM1

COM100

Ch0

Ch1

Ch100

Ch101

5355

If a power supply that meets safety standards is used and only feeds the operator

panel, there is no problem. See 1 in drawing above.

However, if a 24 V unit that also feeds other units is used, there is reason to be

cautious, see 2 in drawing above. The operator panel does not have insulation

that meets safety requirements in the event of a potential short circuit between

230 V AC and 24 V DC. It is assumed that the 24 V feed is secure, for example,

SELV according to EN 60950 (protection against electric shock) and UL 950.

Example:

Hereisanexamplethatexplainswhyasecure24VDCfeedcanberuinedbymixing

24Vrelaycontactswith 230VACrelaycontactsinasmallercontroller. Checkthatthe

clearancesandcreepagedistancesbetween24VDCand230VACfulﬁllEN60950or

UL950. Ifnot,inputaseparate24Vunitintotheoperatorpanel.

If there is a substa

ntial distance between the relay contacts for 24 V DC and

230 V AC, it is OK t

ousethesame24Vdevicesforallfeeds. See3indrawing

above.

Connect 0 V on the 24 V feed to the ground, see 4 in drawing above. This offers

three advantages:

• Safety is incr

eased. The24Vfeedwillnotbeliveintheeventofafaulty

connection o

rshortcircuitbetween0V(24V)and230Vphase.

• Tr a n s ie n t s

on the 24 V feed are connected to the ground.

• No risk tha

t the 24 V feed is at a high level in relationship to the ground. This

is not unu

sual since there is high static electricity.

BeijerElectronics, MAEN082D

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Beijer-electronics iX T12C EN Manual de usuario Pagina 30

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