GE M60 UR Series

5-142 M60 Motor Protection System GE Multilin
5.6 GROUPED ELEMENTS 5 SETTINGS
5
The element stores the basic statistics for the last five successful starts. The following values are retained, available for dis-
play, and accessible via communications: date and time of starting, acceleration time (in seconds), effective acceleration
current (in multiplies of FLC), and peak acceleration current (in multiplies of FLC). Recorded effective acceleration current
and time could be used for fine-tuning of the relay settings.
Figure 5–53: SAMPLE ACCELERATION CURRENTS
• ACCELERATION CURRENT: This setting is only used in the Adaptive mode. The setting defines a constant current
that when applied to the motor would accelerate the motor within the normal acceleration time. The setting is used to
adapt the tripping action when the current is changing significantly during the start, such as due to voltage dips.
• ACCELERATION TIME: This setting specifies the maximum acceleration time. If the motor is not in the running state
when this time expires, the element operates. This setting could be estimated experimentally by starting a given motor
several times under various load and electrical conditions and measuring the starting time. Some security margin
should be applied.
• ACCELERATION MODE: This setting defines the operating mode of the acceleration time element. When set to “Def-
inite Time”, the element times duration of the motor start and operates when the starting time exceeds the
ACCELERA-
TION TIME setting. When set to “Adaptive”, the element uses the effective accelerating current to adapt to the starting
conditions. The operating equation assumes that the accelerating power is proportional to the square of the current
and neglects any current unbalance or impact of the rotor slip. Consequently, in the adaptive mode, the element oper-
ates when the square of the current integrated from the beginning of the start up to a given time exceeds
.
Figure 5–54: ACCELERATION TIME SCHEME LOGIC
833014A1.CDR
time ACCEL. TIME
ACCEL. CURRENT
current
FLA x SERVICEFACTOR
time
ACCEL. TIME
current
FLA x SERVICEFACTOR
i1
i2
i5
i3
i4
i6
(a) (b)
n
2
n
i..
2
2
i
2
1
i
CURRENTACCEL.
+++
=
Acceleration Current
2
Acceleration Time
=Off
ACCELERATION BLOCK
SETTINGS
= Enabled
ACCELERATION
FUNCTION
=On
MOTOR OFFLINE
Definite Time
Adaptive
AND
SETTING
= Definite Time
= Adaptive
ACCCELERATION MODE
SETTING
= Enabled
THERMAL MODEL
FUNCTION
SETTING
= Ia magnitude
= Ib magnitude
MOTOR LINE SOURCE
= Ic magnitude
MAX
SETTINGS
ACCELERATION
CURRENT
RUN
T > ACCELERATION TIME
ACCELERATION TIME
RUN
I
2
T>(ACCEL.CURRENT )
2
×ACCEL.TIME
RUN
CALCULATE:
Peak acceleration current
Effective acceleration current
Acceleration time
FLEXLOGIC OPERANDS
MOTOR ACCEL TIME OP
MOTOR ACCEL TIME DPO
OR
FLEXLOGIC OPERANDS
MOTOR STARTING
MOTOR RUNNING
RECORDS
START DATE
START TIME
ACCELERATION TIME
EFFECTIVE CURENT
PEAK CURRENT
833013A3.CDR