SIMPRO-100
Settings Calculation
4
PRIM-2400C
47
time at six times full load current. For a cold
motor, the curve 10 trip time at six times full load
current is 25 seconds. Table 4.8, page 49 and
Table 4.9, page 49 show the cold motor thermal
limit time versus current for several curves.
Each increase in the curve number yields a
2.5 second increase in the hot motor thermal limit
time at six times full load current.
Continue calculating the balance of thermal
element settings with “Thermal Capacity Alarm
Setting”, page 53.
Example:
Thermal Element Generic Method
Setting
A 4160 V, 800 HP motor is to be protected
using the SIMPRO-100 Relay Thermal
Element Generic Curve Method. The motor
data sheet includes the following
information.
Rated Horsepower (HP) = 800 HP
Rated Voltage (V) = 4160 V
Rated Full Load Current (A) = 101.0 A
Rated Locked Rotor Amps (A) = 620.4 A
Safe Stall Time, Hot = 30 seconds
Service Factor = 1.15
Each increase in generic curve number
increases the hot motor thermal limit time
by 2.5 seconds at six times full load current.
Therefore, we can select the maximum
curve number using the following equation.
Equation 4.1
Phase current transformers having 150:5
ratios are selected for the application. The
SIMPRO-100 Relay settings for the
application are shown below.
Current Transformer Ratio (CTR) =
150/5 = 30
CT Secondary Rating (ITAP) = 5
Full Load Amps (FLA) = 101/30 =
3.36 A secondary
Service Factor (SF) = 1.15
Curve Number (CURVE) = 12
Summary of Contents for SIMPRO-100
Page 1: ...SIMPRO 100 Motor Protection Relay Instruction Manual Document No PRIM 2400C ...
Page 12: ...Contents SIMPRO 100 x PRIM 2400C ...
Page 16: ...Contents SIMPRO 100 xiv PRIM 2400C ...
Page 42: ...3 SIMPRO PC Software SIMPRO 100 40 PRIM 2400C ...
Page 100: ...6 ASCII Serial Port Operation SIMPRO 100 98 PRIM 2400C ...
Page 127: ...SIMPRO 100 Event Analysis 9 PRIM 2400C 125 Figure 9 2 Example SER Report ...
Page 136: ...10 Maintenance Troubleshooting SIMPRO 100 134 PRIM 2400C ...
Page 138: ...A Firmware Versions SIMPRO 100 136 PRIM 2400C ...
Page 206: ...D SIMPRO PC Compatibility Features SIMPRO 100 204 PRIM 2400C ...
Page 214: ...E Motor Thermal Element SIMPRO 100 212 PRIM 2400C ...
Page 230: ...F SIMPRO 100 Relay Settings Sheets SIMPRO 100 228 PRIM 2400C ...
Page 239: ......