Safe Torque Off (Sto) Wiring - Danfoss VLT FC 103 Operating

VLT® Refrigeration Drive FC 103
Operating Guide
• Protection against overload (L). The drive trips when there is an overload with inverse long-time delay trip according to the IEC
60947-2 Standard (I2t=k).
• Protection against short circuit with time delay (S). The drive trips when there is a short circuit with long inverse time-delay
trip (I2t=k ON), or a constant trip time (I2t=k OFF).
•
Instant protection against short circuit (I). The drive trips immediately if there is a short circuit. The trip function (L) is always
available and either (S) or (I) can be selected by the DIP switch[S/I] on the trip unit of the MCCB.
Factory default settings are provided for functions L and I.
• Overcurrent setting (L) is done at 100% of the 1.5 times high overload FLA (I
• Time delay (t1) is selected as 12 s for 6 times of I
• Short circuit instant trip setting (I) is followed. Short circuit trip with time delay (S) is ignored with the factory settings.
• Short circuit instant trip setting (I) is targeted at 300% of the 100% normal overload FLA (I
• Neutral setting (N) is 100%.
• Frequency of operation is set at 50 Hz from the factory.
Illustration 56: MCCB Factory Default Settings

5.17 Safe Torque Off (STO) Wiring

The Safe Torque Off (STO) function is a component in a safety control system. STO prevents the unit from generating the voltage
required to rotate the motor. To run the STO function, more wiring for the drive is required. Refer to the VLT
Operating Guide.
Danfoss A/S © 2020.09
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Electrical Installation
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FC Series - Safe Torque Off
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