2 Engineering
2.8 Switching to the output side
38 DC1-S…20…, DC1-S…OE1 Variable Frequency Drives 05/21 MN040058EN www.eaton.com
2.8 Switching to the output side
Typical applications for switching at the DC1-S… variable frequency drive’s
output include:
• Cases in which a bypass circuit is implemented.
• Cases in which the motor must be de-energized quickly in the event of
an emergency switching off (safety shutdown).
When the motor is switched off, the inverter needs to be disabled first
(the START enable signal must be switched off) before the contacts
(contactor, switch-disconnector) on the variable frequency drive’s output side
are opened.
2.8.1 Contactors
The contactors on the output side of DC1-S… variable frequency drives need
to be sized based on utilization category AC-3 (IEC/EN 60947-4-1) for the
assigned rated motor current and the corresponding rated operating voltage.
When a motor is being switched off, the DC1-S… variable frequency drive’s
output (inverter) must be disabled (the START enable signal must be
switched off) before the contacts are opened.
2.8.2 switch-disconnectors
Switch-disconnectors are used as repair and maintenance switches in
industrial, trade, and building service management applications. At the output
of variable frequency drives, they are primarily used to locally switch off
motors (pumps, fans) that pose a risk of unintended starting during
maintenance or repairs. In order to provide greater safety, these switch-
disconnectors can be locked out with the use of padlocks, meaning they
have characteristics comparable to those of main switches as defined in
EN 60204.
Eaton T0…/MSB/…, P1…/MSB/…, and P3…/MSB/… enclosed switch-
disconnectors are designed for local installation with an IP65 degree of
protection. The internal screening plate ensures that screened motor cables
can be easily connected in a way that meets EMC requirements.
The switch-disconnectors on the output side of DC1-S… variable frequency
drives need to be sized based on utilization category AC-23A (IEC/EN 60947-
3) for the assigned rated motor current and the corresponding rated
operating voltage.
When a motor is being switched off, the DC1-S… variable frequency drive’s
output (inverter) must be disabled (the START enable signal must be
switched off) before the contacts are opened.
For more information and technical data on T0…/MSB/
…, P1…/MSB/…, and P3…/MSB/… switch-
disconnectors, please refer to instruction leaflets
IL008020ZU as well as IL008037ZU.
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