GE 469 Instruction Manual page 201

CHAPTER 5: SETTINGS
469 MOTOR MANAGEMENT RELAY – INSTRUCTION MANUAL
TC ( TC
=
used
TC
used_end
where: TC = thermal capacity used
used
TC = TC
used_start
TC = TC
used_end
the motor is running (= 0 when the motor is stopped)
t = time in minutes
τ = Cool Time Constant (running or stopped)
I = equivalent motor heating current
eq
ol_pkp = overload pickup settings as a multiple of FLA
hot / cold = hot/cold safe stall ratio
100
75
Cool Time Constant= 15 min
TCused_start= 85%
Hot/Cold Ratio= 80%
50
Ieq/Overload Pickup= 80%
25
0
0 30 60 90
Time in Minutes
80% LOAD
100
75
Cool Time Constant= 30 min
TCused_start= 85%
Hot/Cold Ratio= 80%
Motor Stopped after running Rated Load
50
TCused_end= 0%
25
0
0 30 60 90
Time in Minutes
MOTOR STOPPED
Hot/Cold Safe Stall Ratio
The motor manufacturer may provide thermal limit information for a hot/cold motor. The
469 thermal model adapts for these conditions if the
is programmed. This settings value dictates the level of thermal capacity used the relay will
settle at for current levels below the
t τ ⁄
–
TC ) e (
–
used_start used_end
I
hot
  1  
eq
---------------- --------- -
= –
   
ol_pkp cold
value caused by overload condition
used
value dictated by the hot/cold safe stall ratio when
used
100
75
50
25
0
120 150 180
0
100
75
50
25
0
120 150 180 0
FIGURE 5–15: Thermal Model Cooling
OVERLOAD PICKUP LEVEL
) TC
+
used_end
×
100%
Cool Time Constant= 15 min
TCused_start= 85%
Hot/Cold Ratio= 80%
Ieq/Overload Pickup= 100%
30 60 90 120
Time in Minutes
100% LOAD
Cool Time Constant= 30 min
TCused_start= 100%
Hot/Cold Ratio= 80%
Motor Overload
TCused_end= 0%
30 60 90 120
Time in Minutes
MOTOR TRIPPED
HOT/COLD SAFE STALL RATIO
. When the motor is running
(EQ 5.5)
(EQ 5.6)
150 180
150 180
808705A2.CDR
settings
5–57