Application Note: L300P/SJ300 Low Current Trip Function for Pumping Applications Please refer also to the Inverter Instruction Manual AN081804-1
L300P/SJ300 Low Current Trip Function for Pumping Applications Sometimes it is desirable to have the inverter trip when running at constant speed and the motor current falls below a certain threshold level. In the case of a pump, this would be indicative of absence of fluid in the pump, and hence no load on the motor. This functionality could also be useful in other applications where it is important to know that there is no load on the motor.
TIMING CHART [OL] AND [FA1] n [OL] AND [FA1] o [OL] (N.C) n [OL] (N.C) o [FA1] (N.O.) o C041 n Motor Current Output Frequency Time Hitachi America, Ltd. © 2004 Hitachi America, Ltd.
TIMING CHART (continued) [OL] AND [FA1] p [OL] AND [FA1] q [OL] (N.C) p [OL] (N.C) q [FA1] (N.O.) q p C041 TRIP Motor Current p Output Frequency q Hitachi America, Ltd. © 2004 Hitachi America, Ltd.
WIRING DIAGRAM L300P Inputs 1 2 Outputs 3 11A 4 11C 5 12A CM1 12C Hitachi America, Ltd. © 2004 Hitachi America, Ltd.
SJ300 Setup Since the intelligent outputs are solid state and share a common connection internally, the SJ300 setup is slightly different. Table 2 shows the SJ300 setup. The wiring diagram is below. Instead of using a logical AND of the two output signals, we use logical OR, which is achieved by paralleling the outputs as shown. We then invert the two output signals ([OL] and [FA1]) and invert the [EXT] input versus the setup for L300P. The resulting Boolean logic provides the identical functionality.
