Mitsubishi Electric FR-A800, Instruction Manual

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Parameters (M) Monitor display and monitor output signal
FR-A800 5 - 375
Low speed detection (LS signal, Pr. 865)
●
When the output frequency (refer to the table below) drops to the Pr. 865 "Low speed detection"
setting or lower, the low speed detection signal (LS) is output.
●
In speed control under Real sensorless vector control, vector control or PM sensorless vector
control, when the frequency drops to the Pr. 865 setting, the output torque exceeds the Pr. 874
"OLT level setting" setting, and this status continues for 3 s, a fault (E.OLT) appears and the inverter
output stops.
●
For the LS signal, set "34 (positive logic) or 134 (negative logic)" in any of Pr. 190 to Pr. 196 (output
terminal function selection) to assign the function to the output terminal.
Speed detection hysteresis (Pr. 870)
●
This function prevents chattering of the speed detection signals. When an output frequency
fluctuates, the following signals may repeat ON/OFF (chatter):
– Up to frequency signal (SU)
– Speed detection signal (FB, FB2, FB3)
– Low speed output signal (LS)
Setting hysteresis to the detected frequency prevents chattering of these signals.
Fig. 5-172:
Low speed detection
I002628E
Fig. 5-173:
Output of the speed detection (FB) signal
I002629E
Fig. 5-174:
Output of the up to frequency (SU) signal
I002858E
LS
OFF ON
ON
Time
Pr. 865
Ou
tp
ut
fr
eque
nc
y
(H
z)
FB
Pr. 42
OFF OFF
ON
ON
ON
Output
frequency
(Hz)
Pr. 870
Example of the speed detection (FB) signal
Pr. 870
Pr. 870
Pr. 870
Pr. 870
Pr. 41
SU output
level
Set
frequency
ON
Output frequency
(Hz)
Time
ON
ON
SU signal
SU output
level
Pr. 41
Pr. 870
Pr. 870
Pr. 870
Pr. 870