1MAC050144-MB C
Section 4
Protection functions
615 series ANSI
211
Technical Manual
4.1.10.4
Operation principle
The function can be enabled and disabled with the
Operation
setting. The corresponding
parameter values are Enable and Disable.
The operation of phase-reversal protection can be described by using a module diagram.
All the modules in the diagram are explained in the next sections.
Figure 98:
Functional module diagram
Level detector
The level detector compares the negative sequence current to the set
Pickup value
. If the
I
2
value exceeds the set Pickup value, the level detector sends an enable signal to the timer
module.
Timer
Once activated, the timer activates the
PICKUP
output. When the operation timer has
reached the set
Trip delay time
value, the
TRIP
output is activated. If the fault disappears
before the module trips, the reset timer is activated. If the reset timer reaches the value of
200 ms, the trip timer resets and the
PICKUP
output is deactivated.
The timer calculates the pickup duration value PICKUP_DUR which indicates the ratio of
the pickup situation and the set trip time. The value is available through the Monitored data
view.
4.1.10.5
Application
The rotation of a motor in the reverse direction is not a desirable operating condition.
When the motor drives fans and pumps, for example, and the rotation direction is reversed
due to a wrong phase sequence, the driven process can be disturbed and the flow of the
cooling air of the motor can become reversed too. With a motor designed only for a
particular rotation direction, the reversed rotation direction can lead to an inefficient
cooling of the motor due to the fan design.
In a motor, the value of the negative sequence component of the phase currents is very
negligible when compared to the positive-sequence component of the current during a
healthy operating condition of the motor. But when the motor is started with the phase
connections in the reverse order, the magnitude of I
2
is very high. So whenever the value
of I
2
exceeds the pickup value, the function detects the reverse rotation direction and
provides an trip signal that disconnects the motor from the supply.
PICKUP
TRIP
Level
detector
BLOCK
I
2
Timer
t
Summary of Contents for 615 Series ANSI
Page 1: ...Relion Protection and Control 615 series ANSI Technical Manual ...
Page 2: ......
Page 29: ...1MAC050144 MB C Section 615 series ANSI 22 Technical Manual ...
Page 389: ...Section 4 1MAC050144 MB C Protection functions 382 615 series ANSI Technical Manual ...
Page 485: ...Section 6 1MAC050144 MB C Supervision functions 478 615 series ANSI Technical Manual ...
Page 635: ...Section 10 1MAC050144 MB C Other functions 628 615 series ANSI Technical Manual ...
Page 711: ...Section 16 1MAC050144 MB C Glossary 704 615 series ANSI Technical Manual ...
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