GE 869 - Page 469

CHAPTER 4: SETPOINTS CONTROL
869 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL 4–337
TC USED MARGIN
Range: 0 to 25% in steps of 1%
Default: 25%
Setpoint values in the range of 0 to 25% specify the margin to be included in the
calculation of the adjusted Thermal Capacity Used at start value.
Figure 4-143: Thermal Start Inhibit logic diagram
894084A4.cdr
SETPOINT
TC Used Margin
TC
L
FlexLogic Operands
Thermal Inhibit OP
ACTUAL VALUES
TCU > 100 % - TC
ADJ
TC
ADJ
=TC
L
+ ( TC Used
Margin /100 %) x TC
L
TC
ADJ
TCU
85%
Thermal Lockout Time
Learned TCU (TC L )
SETPOINT
Function
FlexLogic Operands
Motor Stopped
AND
FlexLogic Operands
Thermal Inhibit PKP
LED: Start Inhibit
TC
ADJ
CTCS x ln ( TCU /(100%-TC
ADJ
))
Setpoints/ System / Motor
Number of starts to learn (N)
(1 to 5) default: 3
Thermal Capacity Used
ACTUAL VALUE
Maximum of N values
Calculate Learned TCU (TC
L
)
TC
L
Stored in non - volatile memory
Motor Tripped
OR
0
1
AND
AND
OR
“N” Start history not avail. = 1
OR
RUN
Enabled = 1
FlexLogic Operands
Start Inhibit
SET
RESET
TCU < 15%
LATCH
TCU = 100%
SETPOINT
Trip Function
Disabled = 1
AND
From Thermal Model
AND