Overview
Overview
An electric motor (B) provides input to a 75:1 gear reducer (GR), which drives two fluid pumps (FP). See FIG. 1. The stroke positions of the two pumps are offset to achieve consistent flow from the pump assembly. See FIG. 2.
B
The optional sensor circuit includes a top dead center (TDC) sensor which assists software in measuring motor speed, and a pressure transducer (PT) with circuit board, which measures fluid pressure at the pump out- let. The Graco VFD software mimics the effect of a cam- shaft, constantly adjusting motor speed to keep steady fluid flow and achieve minimal pressure variation. The output shaft of the gearbox and the connecting rods experience the effect of the imaginary camshaft by speeding up when the pressure drops (pump lower is at a changeover) and slowing down when pressure increases (both lowers are pumping).
TDC (behind cover)
FP
GR
PT
FP
The VFD can be controlled by a local control box mounted in the hazardous area, via communication pro- tocol (such as modbus), or directly from the keypad.
FIG. 3 shows a layout of a typical North American sys- tem. The pump (A) may be controlled by a local control box (C) mounted in the hazardous area, a variable fre- quency drive (D) mounted in the non-hazardous area, or remotely from a computer (Y). See manual 311592 for pump and accessory installation information.
ti8317c
FIG. 1. E-Flo Electric Circulation Pump
ti8321a
FIG. 2. Cutaway Showing Offset Stroke Positions
8 | 311593N |
