Application And Setting Notes - Siemens SIPROTEC 5 7UM85 Manual

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Application and Setting Notes

The 7UM85 device manual describes the basic setting notes for all the protection functions.
This chapter provides the additional application and setting notes particularly for the protection device which
is used as the protection of explosion-proof motors.
Motor Differential Protection
The Motor differential protection function:
•
Detects multiphase short circuits in motors
•
Detects ground faults during the operation of motors with a grounded neutral point
•
Keeps stable during startup processes with current-transformer saturation through intelligent saturation
recognition methods
•
Triggers safely in the case of the internal high-current faults through an additional high-current stage
You can find more information in chapter 6.5 Motor Differential Protection in the SIPROTEC 5, 7UM85
Device Manual.
Overcurrent Protection
If the motor runs without overcurrent protection, the Overcurrent protection, phases function and the Over-
current protection, ground function in the 7UM85 can be activated.
You can find more information in chapters 6.11 Overcurrent Protection, Phases and 6.13 Overcurrent
Protection, Ground in the SIPROTEC 5, 7UM85 Device Manual.
Protection for the Unbalanced Load
The Negative-sequence protection function can be used to protect the unbalanced load within the operating
range from 0.1 ⋅ I
When the current exceeds 10 ⋅ I
the motor against a phase failure and an asymmetrical load.
You can find more information in chapters 6.13 Overcurrent Protection, Ground and 6.54 Negative-
Sequence Protection in the SIPROTEC 5, 7UM85 Device Manual.
Undervoltage Protection
If voltage transformers are used, the Undervoltage protection function can also be applied to detect an
unbalanced load caused by the phase failure or the inadmissible voltage dip.
You can find more information in chapter 6.28 Undervoltage Protection with 3-Phase Voltage in the
SIPROTEC 5, 7UM85 Device Manual.
Motor-Starting Time Supervision
The signal Motor starting is detected in the Motor monitor function through the Motor-state detection
function block. If the maximum current of all 3 phases of the motor is larger than the parameter
Curr.thres.starting, the motor changes to the
The starting time is determined by the motor temperature. You can set the maximum starting time for a cold
motor state or a warm motor state. You can also set the per-unit value of the starting current with the motor
SIPROTEC 5, Additional Information on the Protection of Explosion-Proof Motors with Type of Protection Increased Safety e,
Manual
C53000-H5050-C078-1, Edition 03.2019
to 10 ⋅ I .
rated rated
, the Overcurrent protection, ground function can be activated to protect
rated
starting state .
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