Short-Time Protection

Presentation

Short-time protection on MicroLogic 6 E-M trip units protects all types of motor applications against short-circuit currents.

Operating Principle

Short-time protection is definite time. It can be configured as the Isd pickup.

Tripping curve:

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The short-time protection parameters are: B: Ir Long-time protection pick-up D: Isd Short-time protection pick-up E: tsd Short-time protection fixed time delay

Setting the Short-Time Protection

Set the Isd pickup and tsd time delay:

• With the keypad on the MicroLogic trip unit

• With EcoStruxure Power Commission software (password-protected)

• By sending a setting command using the communication network (password-protected)

Isd Pickup Setting Value

The Isd pickup setting value is in multiples of Ir.

The default Isd pickup setting value is 5 x Ir (minimum value).

The pickup setting range on the keypad is 5–13 x Ir. The increment is 0.5 x Ir.

The accuracy range is +/-15%.

tsd Time Delay Value

The time delay cannot be adjusted.

• The hold time is 20 ms.

• The maximum breaking time is 60 ms.