Emerson Vilter VSS - Electrical Connections; Field Wiring Instructions

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Section 3 • Installation
VSS/VSM/VSH/VSSH • Installation, Operation and Maintenance Manual • Emerson • 35391SD
Electrical Connections
Single screw compressor units are shipped with all pack-
age mounted controls wired. The standard control pow-
er is 115 volts 60 Hertz, single phase. If a 115 volt supply
is not available, a control transformer may be required.
The power source must be connected to the control
panel according to the electrical diagrams.
The units are shipped without the compressor mo-
tor starter. Field wiring is required between the eld
mounted starters and package mounted motors, see
Field Wiring Instructions.
Additional control wiring in the eld is also required.
Dry contacts are provided in the control panel for start-
ing the screw compressor motor. These contacts are to
be wired in series with the starter coils. A current trans-
former is supplied along with the compressor unit, and
is located in the motor junction box. This transformer is
to be installed around one phase of the compressor mo-
tor starter. A normally open auxiliary contact from the
compressor motor starter is also required.
Terminal locations for this wiring can be found on the
wiring diagram supplied with this unit. Additional as-
pects of the electrical operation of the single screw units
are covered in the start up and operation section of this
manual.
Field Wiring Instructions
NOTE
This procedure denes steps required to wire Vission
20/20 micro-controller for the following items:
Compressor Motor Starter Auxiliary Contact, High
Level Shutdown, Oil Separator Heater(s), Oil Pump
Start and Compressor Starter.
Follow supplied wiring diagram for detailed wiring.
Refer to Figure 3-12
1. Control power of 115 VAC 50/60 HZ must be wired
to left side of terminal blocks inside the Vission
20/20 cabinet. Line power (1B) shall be connected
to 15-amp circuit breaker, CB1. Neutral (1N) is con-
nected to any N terminal blocks. Number of line
power feeds required to panel is dependent upon
number supplied on compressor, see Figure 3-12.
2. An auxiliary contact from compressor motor starter
is required. Connect isolated contact to terminal
blocks 1 and 31.
3. A dry contact from control relay CR11 must be wired
to compressor motor starter coil. This dry contact is
wired to terminal blocks according to supplied draw-
ing. Control power for this coil should come from a
source, which will be de-energized with compressor
disconnect.
4. A dry contact from control relay CR12 must be wired
to oil pump motor starter coil. This dry contact is
wired to two terminal blocks according to supplied
drawing. Control power for this coil should come
from a source, which will be de-energized with com-
pressor disconnect.
5. An auxiliary safety cutout is available to shut down
compressor package. A dry contact must be sup-
plied and wired to terminal blocks 1 and 32. The
jumper installed on terminal blocks must be re-
moved to use this cutout. If contact is closed, it will
allow compressor to run. If contact opens at any
time, compressor will shut down.
6. Indication of compressor shutdown status is also
available. There is an output on terminal blocks 18
and N where a relay coil can be wired. For output, an
energized state represents a “safe” condition. A de-
energized state indicates a loss of voltage to relay
coil or a “failure” has occurred.
7. Line power for oil separator heaters are required to
be wired from the starter panel, see Figure 3-13.
8. Units with V-PLUS
TM
oil cooling, L1 must connected
to a fuse in V-PLUS panel, and L2 must be connected
to a neutral terminal block, see Figure 3-14.
NOTE
There is a dot on one side of the current transformer.
This dot must face away from the motor.
9. Current transformer supplied in compressor motor
conduit box should be checked to ensure that mo-
tor leads of one leg are pulled through the trans-
former. Typically, a wye delta started motor should
have leads 1 and 6 pulled through this transformer
for a 6 lead motor. However, this should always be
checked as different motors and starting methods
will require different leads to be used.
NOTE
For Compressor unit using PLC micro-controller,
please refer to the Single Screw Compressor PLC
Operation Manual (35391CM) for details.