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E LEC TRON I C COM PAC T STA RTE R
| M A N UA L
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8
Typical circuits for HF range types with
integrated emergency stop
In circuits in potentially dust/gas-explosive areas of zones 21 and 22, equipment connected to this circuit
must be guaranteed to comply with category 2D or 3D or be certified as such.
A zone 21 area is classified as a place in which an explosive atmosphere consisting of a mixture with air or
flammable substances in the form of powder or dust is likely to occur in normal operation occasionally.
(Typical North American Marking to NEC 500)
A zone 22 area is classified as an atmosphere where a mixture of air and flammable substances in the
form of powder or dust is not likely to occur in normal operation, but if it does occur, it will persist
for a short period only.
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8.1
Prevention of cross-error circuit
Since the control supply voltage or the control input voltage of the hybrid motor starter is disconnected via a single channel
to the safety relay, this type of installation is allowed according to SIL 3, only if error prevention for cross circuits is
permitted. A cross-circuit happens if the connecting wire is bruised or damaged.
Error prevention of cross-circuit is permitted, if the hybrid motor starter and the safety relay are installed in the same
control cabinet.
If the hybrid motor starter and safety relays are not in the same control cabinet a dual channel connection is recommended.
