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Over Current Level 1- Jam
This identifies a jam condition for a "running" motor. Fault occurs if after start process has ended, motor
average current increases above O/C Level 1 setting value for more than O/C LEVEL 1 Delay.
Auto reset, when Enabled, occurs when current decreases below O/C Level 1, or when motor stops or trips.
Over Current Level 2 - Short
This identifies short circuit condition. Fault occurs when any of the motor's line currents exceeds O/C LEVEL 2-
Short value, for more than O/C LEVEL 2 Delay time.
Auto reset, when Enabled, occurs when current decreases to below the O/C Level 2- Short value, or when trips
motor.
Notes:
1. True RMS line currents are measured, disregarding the average "DC" value. It is designed to prevent
nuisance tripping at the very beginning of the starting process (during which DC decaying current is
superimposed on the AC Current).
2. Minimum setting of "O/C Level 2 Delay" is 0. At 0 setting, the actual time delay is less than 70 ms.
3. O/C Level 2- Short is prevented when the highest of any of the line currents exceeds Current Inhibit setting.
It is designed to prevent opening of motor contactor under high short circuit conditions to protect its contacts
from being damaged. Fault display: "O/C Level 2- Short".
4. Thermal level 2 (Overload) overrides "Current Inhibit" setting.
Thermal Level 1 and 2
The MPS3000 simulates the thermal condition of the motor and stores it in a thermal register. The content of
the thermal register is called "Thermal Capacity". It simulates the motor temperature. Thermal capacity of 100%
is equivalent to a motor running at the absolute maximum allowed temperature. At this point the motor must be
tripped.
The following parameters are used to calculate the Thermal Capacity.
Curve Multiplier
This is a multiplier of the basic standard curve. It enables to shift the entire overload curve. For example, when
Curve Multiplier is set to 1, time to trip of a cold motor at 2*In is 29.1 Sec. If Curve Multiplier is set to 10, time to
trip of a cold motor at 2*In is 291 Sec.
Overload Pickup
Thermal Level 2 is not active for currents below the "Overload Pickup" value. For a standard motor, leave
Overload Pickup at its default value of 105%. When current increases above this value a fault will occur after a
given time. This time depends on the present value of the "Thermal Capacity", on the current level and on
"Curve Multiplier" parameter.
Hot/Cold Ratio
This parameter, determines the ratio of the available "Thermal Capacity" for a Hot Motor and for a Cold Motor.
The "Thermal Capacity" of a Hot motor, is (100 - Hot/Cold Ratio).
Cold Condition - When the motor is stopped for a long time, its "Thermal Capacity" is zero. Therefore, for a cold
motor, all the 100% of "Thermal Capacity" are available for heating (before a trip occurs).
Hot Condition - When a motor is running, its temperature increases, and after it has been running for a long
time at a current, slightly below the Overload Pickup value, a "Hot Condition" has been created. Now, less than
100% of the "Thermal Capacity" is available.
Example: If Hot/Cold Ratio is set to 60%, then for a "Hot" motor, 40% of the "Thermal Capacity" was used,
leaving 60% for additional heating.
For a motor, running for a prolonged time, at lower than "Overload Pickup" current value, the "Thermal
Capacity" is related to the value of the current.
For Example, if motor current is only ½ of the Overload Pickup level, then (K=(½)*40%=20%) only 20% of the
"Thermal Capacity" has been used, leaving 80% for additional heating.
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