GE 869 - Page 264

4–132 869 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
PROTECTION CHAPTER 4: SETPOINTS
typically used to detect a voltage loss condition. If a voltage loss has been detected
while the motor accelerates, the thermal curve is switched to one based on the
programmed 100% voltage thermal limit:
Eq. 24
VD STALL CURRENT @ MIN V
Range: 1.50 to 20.00 FLA in steps of 0.01
Default: 4.50 x FLA
The setting defines the locked rotor current level at minimum motor voltage (I
1
).
VD STALL TIME @ MIN V
Range: 0.1 to 1000.0 in steps of 0.1
Default: 20.0 seconds
The setting defines the maximum time that the motor is allowed to withstand the locked
rotor current at minimum motor voltage (t
1
).
VD ACCEL. INTERSECT @ MIN V
Range: 1.50 to 20.00 in steps of 0.01
Default: 4.00 x FLA
The setting defines the starting current level corresponding to the crossing point
between the acceleration thermal limit at minimum voltage and the programmed relay
overload curve (I
2
). This value can be typically determined from motor acceleration
curves. The value at the breakdown torque for the minimum voltage start is
recommended for this setting.
VD STALL CURRENT @ 100% V
Range: 1.50 to 20.00 FLA in steps of 0.01
Default: 6.00 x FLA
The setting defines the locked rotor current level at the rated motor voltage (I
3
).
VD STALL TIME @ 100% V
Range: 0.1 to 1000.0 in steps of 0.1
Default: 10.0 seconds
The setting defines the maximum time the motor is allowed to withstand the locked
rotor current at rated motor voltage (t
3
).
VD ACCEL. INTERSECT @ 100% V
Range: 1.50 to 20.00 in steps of 0.01
Default: 5.00 x FLA
The setting defines the starting current level corresponding to the crossing point
between the acceleration thermal limit at rated voltage and the programmed relay
overload curve (I
4
). The value can be typically determined from the motor acceleration
curves. The current value at the breakdown torque for the 100% voltage start is
recommended for this setting. The voltage dependent overload curves are shown in the
following figure.