Section 6
1MAC050144-MB C
Supervision functions
460
615 series ANSI
Technical Manual
6.6.2
Function block
Figure 244:
Function block
6.6.3
Functionality
The motor startup supervision function 66/51LRS is designed for protection against
excessive starting time and locked rotor conditions of the motor during starting. For the
reliable operation of the motor, the thermal stress during the motor starting is maintained
within the allowed limits.
The starting of the motor is supervised by monitoring the TRMS magnitude of all the phase
currents or by monitoring the status of the circuit breaker connected to the motor.
During the startup period of the motor, 66/51LRS calculates the integral of the I²t value. If
the calculated value exceeds the set value, the trip signal is activated.
66/51LRS has the provision to check the locked rotor condition of the motor using the
speed switch, which means checking if the rotor is able to rotate or not. This feature trips
after a predefined operating time.
66/51LRS also protects the motor from an excessive number of startups. Upon exceeding
the specified number of startups within certain duration, 66/51LRS blocks further starts.
The restart of the motor is also inhibited after each start and continues to be inhibited for
a set duration. When the lock of startup of motor is enabled, 66/51LRS gives the time
remaining until the restart of the motor.
66/51LRS contains a blocking functionality. It is possible to block function outputs, timer
or the function itself, if desired.
6.6.4
Operation principle
The function can be enabled and disabled with the
Operation
setting. The corresponding
parameter values are Enable and Disable.
The operation of the motor startup supervision function can be described using a module
diagram. All the modules in the diagram are explained in the next sections.
I_A, I_B, I_C
Summary of Contents for 615 Series ANSI
Page 1: ...Relion Protection and Control 615 series ANSI Technical Manual ...
Page 2: ......
Page 29: ...1MAC050144 MB C Section 615 series ANSI 22 Technical Manual ...
Page 389: ...Section 4 1MAC050144 MB C Protection functions 382 615 series ANSI Technical Manual ...
Page 485: ...Section 6 1MAC050144 MB C Supervision functions 478 615 series ANSI Technical Manual ...
Page 635: ...Section 10 1MAC050144 MB C Other functions 628 615 series ANSI Technical Manual ...
Page 711: ...Section 16 1MAC050144 MB C Glossary 704 615 series ANSI Technical Manual ...
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