Emerson Vilter Vission 20/20, Operation And Service Manual

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6 – 19
Section 6 • Compressor Control
Vission 20/20 • Operation and Service Manual • Emerson • 35391SC 2.7
Compressor Size Tubing Lines
Toggle
Switch Outlet Port
(de-energized)
VSM152-401 (205mm)
Low-Medium SIG CW 3 o’clock
Low-High N/A N/A
Medium-High N/A N/A
VSM501-701 (240mm)
Low-Medium SIG CW 3 o’clock
VSS751-901 (280mm)
VSS1051-1301
(310mm)
Low-High SIG CCW 12 o’clock
VSS1551-2101
(350mm)
Medium-High SIG CCW 12 o’clock
VSS2401-3001
(401mm)
Low-Medium Incomplete Incomplete
Low-High Incomplete Incomplete
Medium-High Incomplete Incomplete
12 o’clock outlet port 3 o’clock outlet port
Figure 6-17. Port Inlet and Outlet Flow Directions
Table 6-1. Compressor Size and Liquid Injection Outlet Port Direction
Liquid Injection Outlet Port Direction
The toggle switch (S1) on the circuit board is used to se-
lect which port is the preferred “Pre Start-Up” outlet posi-
tion. The valve shall be at the lowest-pressure outlet posi-
tion at “Pre Start-Up” (i.e. low or medium, depending on
tubing positions).
In the “SIG CCW” position, the actuator moves CCW
when the signal is energized during operation (based on
the switch pressure), until it reaches the limit - this makes
the 3 o’clock port the outlet port (Figure 6-17, right im-
age). Conversely, the other switch position, “SIG CW,”
makes the 12 o’clock port the outlet when the signal is
energized during operation (Figure 6-17, left image).
Each rotor diameter has a different port configuration on
the compressor housing.
For 205mm: there are only medium and low-ratio ports,
both of which are located on both top and bottom of the
housing.
For 240mm-350mm: low ports are located on the top
and bottom of the compressor, the medium port is on
the top, and the high port is on the bottom.
For 401mm: all three ports are located on both the top
and bottom of the housing.