ABB 615 series Technical Manual page 761

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1MAC059074-MB A

615 series ANSI

Technical Manual

The activation of the BLOCK input signal resets the thermal stress calculator and

deactivates the OPR_IIT output.

Stall protection

This module is activated only when the selected Operation mode setting value is "IIt &

stall" or "IIt & stall, CB".

The start-up current is specific to each motor and depends on the start-up method used,

such as direct online, autotransformer and rotor resistance insertion. The start-up time is

dependent on the load connected to the motor.

Based on the motor characteristics supplied by the manufacturer, this module is required

if the stalling time is shorter than or too close to the starting time. In such cases, a speed

switch must be used to indicate whether a motor is accelerating during start-up or not.

At motor standstill, the STALL_IND input is active. It indicates that the rotor is not

rotating. When the motor is started, at certain revolution the deactivation of the

STALL_IND by the speed switch indicates that the rotor is rotating. If the input is not

deactivated within Lock rotor time, the OPR_STALL output is activated.

The module calculates the duration of the motor in stalling condition, the STALL_RL

output indicating the percent ratio of the start situation and the set value of Lock rotor

time. The value is available in the Monitored data view.

The activation of the BLOCK input signal resets the operation time and deactivates the

OPR_STALL output.

Cumulative start-up protection

This module protects the motor from an excessive number of start-ups.

Whenever the motor is started, the latest value of START_TIME is added to the existing

value of T_ST_CNT and the updated cumulative start-up time is available at T_ST_CNT.

If the value of T_ST_CNT is greater than the value of Cumulative time Lim, the

LOCK_START output is activated and lockout condition for the restart of motor is enabled

during the time the output is active. The LOCK_START output remains high until the

T_ST_CNT value reduces to a value less than the value of Cumulative time Lim. The start

time counter reduces at the rate of the value of Counter Red rate.

The LOCK_START output becomes activated at the start of MOT_START. The output

remains active for a period of Restart inhibit time.

Protection functions

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