ElmoMC SimplIQ Command Reference - Manual (Page 122)

PL[N] - Peak Duration and Limit
Purpose:
ƒ
PL[1] defines the motor maximum peak current, in amperes.
ƒ PL[2] defines the motor maximum peak duration, in seconds.
This parameter is used to protect the motor (or the drive) from over-current, and to
protect the load from excessive torque. The motor current (torque) command is normally
limited to its peak limit, as defined by PL[1]. After a short period of torque demand
higher than C[1], the torque command limit is decreased to CL[1]. If the current
command has been raised to PL[1] from zero, after the time specified for peak duration
(PL[2], in seconds), the motor current command will be limited to CL[1]. The motor
current command remains limited to CL[1] until enough time has passed for the average
requested torque command to fall below 90% of CL[1].
The LC flag indicates that the current is limited to its continuous limit.
Torque limits PL[N] and CL[N] may be changed dynamically while the motor is on.
Attributes: Type: Parameter, Real
Source: Program, RS-232, CANopen
Restrictions: None
Default values:
PL[1]=0, PL[2]=3 (RS), Non-volatile
Range: PL[1]: [0…MC]
PL[2]: [1…3]
Index range: [1, 2]
Unit modes: All
Activation: Immediate
Notes:
ƒ Always specify a PL[1] value that can be reached. Do not specify PL[1]>V
B
/R
M
,
where V
B
is the DC motor supply voltage and R
M
is the motor resistance. You
should choose a PL[1] value small enough so that at peak current, there is enough
voltage to drive current changes. Otherwise, at large currents, the drive speed of
response will be limited by voltage saturation, and the controller performance will
decrease.
ƒ Allowed peak current may be saturated at a level lower than the PL[1] value when
the PWM frequency is increased with the XP[2] command. The actual peak
saturated value in amperes can be retrieved with the WS[33] command.
ƒ The definition used here for an ampere of three-phased motor current is explained
in the “Units” section of the
SimplIQ Software Manual.
ƒ The peak duration PL[2] specifies the time it takes to switch from the peak limit to
the continuous limit, when the current PL[1] and PL[1]=MC. The actual time
period for which the peak current may be applied can, however, vary significantly
from PL[2].
ƒ If PL[1] < MC, a longer time may be allowed for the peak current, in order to
protect the drive itself.
SimplIQ Command Reference Manual Alphabetical Listing
MAN-SIMCR (Ver. 4.5)
3-109