Programming
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D-56
890CS Common Bus Supply - Frames B & D; 890CD Common Bus Drive and 890SD Standalone Drive - Frames B, C & D
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MOTR DRV LIMIT
SETUP::MOTOR CONTROL::MOTR DRV LIMIT
Designed for BRUSHLESS SERVO Motor Control Mode.
The purpose of the Motor Drive Limitation is to automatically reduce the drive current limit in response to prolonged overload
conditions. As the motor current exceeds the AIMING POINT level, the excess current is integrated. Motor current is allowed
to flow at 200% of the permanent Drive current for a DELAY time. When this point is reached, the current limit is clamped to
100% of the permanent Drive current.
Under normal conditions, the drive current limit is set to the minimum value between :
-
200% of the permament Drive current (STACK CURRENT parameter of the FEEDBACKS Function Block)
-
MAX CURRENT parameter of the PMAC MOTOR Function Block
If the Drive speed becomes lower than 2.5 Electrical Hz, the DELAY time is automatically reduced to 25% of its value.
There is also a motor protection based, on the rms current flowing in motor phases. This protection is named I2T and is based
on two parameters of the PMAC MOTOR function block: PERM CURRENT and THERMAL TIME CST.
The level of motor load (I2T MOTOR LOAD) is given as percentage, and represents 100% if a current equal to the PERM
CURRRENT flows in motor phases for a THERMAL TIME CST time.
Parameter Descriptions
AIMING POINT
PREF: 84.01
Default: 105.00 %
Range: 50.00 to 150.00%
Determines the level of the current limit ( % of the permanent Drive current ) to begin integer the current.
DELAY
PREF: 84.02
Default: 4.0s
Range: 0.5 to 4.0s
Determines the maximum allowed overload duration for having 200% of the permanent Drive current.
If the Drive speed becomes lower than 2.5 Electrical Hz , the DELAY time is automatically reduced to 25% of its value.
