9-3
9.4 Compliance with EN954-1, Category 3
9.4.1 General
In FRENIC-MEGA series of inverters, opening the hardware circuit between terminals [EN] and [PLC] stops the output transistor,
coasting the motor to a stop. (EN: Enable input) This is the Safe Torque Off (STO) on prescribed in EN60204-1, Category 0
(Uncontrolled stop) and compliant with EN954-1, Category 3.
Note:
Depending on applications, it may be necessary (for end-user) to apply additional measures, such as ‘brake function’, to
prevent movement. Also protect against possible electrical hazard(s) at motor terminals.
Use of terminals [EN] and [PLC] eliminates the need of external safety circuit breakers while conventional inverters need those
breakers to configure the EN954-1 Category 3 compliant safety system.
9.4.2 Notes for compliance to EN954-1 category 3
(1) Wiring for terminal [EN]
- When using terminal [EN], be sure to remove the short-circuit wire from terminals [EN] and [PLC], which has been
connected at the shipment.
- '[EN] & [PLC]' terminals are safety related wire connections and therefore careful installation practices shall be applied to
ensure no 'short-circuit(s)' can occur to these connections.
- For opening and closing the hardware circuit between terminals [EN] and [PLC], use safety approved components such as
safety switches and safety relays that comply with EN954-1, Category 3 or higher to ensure a complete shutoff.
- Be sure to use shielded wires for connecting terminals [EN] and [PLC] and ground the shielding layer. Do not connect/mix
any other control signal wire within the same shielded core.
- It is the responsibility of the machinery manufacturer to guarantee that a short-circuiting or other fault does not occur in
wiring of external safety components between terminals [EN] and [PLC].
Fault
examples:
• Terminals [EN] and [PLC] are short-circuited due to the wiring being caught in the door of the control panel so that a
current continues to flow in terminal [EN] although the safety component is OFF and therefore the safety function
will/may NOT operate
• The wiring is in contact with any other wire so that a current continues to flow in terminal [EN] and therefore the safety
function will/may NOT operate
Summary of Contents for FRENIC-MEGA
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