GE M60 Instruction Manual page 291

CHAPTER 5: SETTINGS
10000
— This setting applies only to the IEC motor curve and is applied as described in the
IEC CURVE k FACTOR
setting description. See the IEC 255-8 standard for details on its application.
CURVE
— This setting specifies the thermal time constant for IEC motor curves in the previous equations
IEC CURVE TIME CONSTANT
per the IEC 255-8 standard. When the IEC motor curves are selected, the M60 calculates the time to trip using the IEC255-
8 cold curve and IEC255-8 hot curve equations and increases thermal capacity used as defined by the thermal capacity
used equation earlier. If the overload disappears or the motor is tripped (stopped), then the thermal capacity used
decreases as per the following equations to simulate motor cooling, depending on the motor status and the values
programmed for the
COOL TIME CONSTANT RUNNING
If the IEC curve is selected, then the following applies:
• For two-speed motor applications, the
speeds
• Voltage dependent overload curves are not applicable
• The motor status is evaluated using motor FLA (I
THERMAL MODEL TD MULTIPLIER
different curves. The TD multiplier value is used to select the curve that best matches the thermal characteristics of the
protected motor.
If thermal model curve is selected as "Motor," then the
"15.00" as indicated in the following Standard Motor Curves diagram.
M60 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
Figure 5-76: Impact of the thermal model curve effect setting
1000
100
10
1
0
Stator current (multiples of FLA)
and
COOL TIME CONSTANT STOPPED
IEC CURVE k FACTOR
) and the
b
— This multiplier is used to shift the overload curve on the time axis to create a family of the
THERMAL MODEL TD MULTIPLIER
SF = 1.15, EFFECT = shift
SF = 1.15, EFFECT = cutoff
5 8
settings.
and
IEC CURVE TIME CONSTANT
setting
IEC CURVE k FACTOR
can be specified between "1.00" and
GROUPED ELEMENTS
THERMAL MODEL
settings are used at both
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