Nederman 40103102, User Manual

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VAC 20
4 Main components
4.1 Overview
Figure 1 shows the main components of the VAC 20
unit. These are as follows:
1
Acoustic enclosure.
2 Motor.
3 2-stage high-pressure fan.
4 Start-up valve. SUV 200 which also serves as a
backflush valve. 24 V DC is supplied as standard
but a solenoid for 24 V AC is also enclosed.
5 Anti-surge valve. (TVS76, Control motor and silen-
cer).
6 VAC 20-1500/2500/3000: Flow restrictor FR 160,
see also
Figure 4 .
7 Manual reset thermal switch for the fan bearings.
8 Belt transmission.
The optional inlet silencer is shown in Figure 2 .
1 Optional: Inlet silencer for extra low noise levels
indoors.
4.2 Connections
Figure 5 is a schematic diagram of the normal connec-
tions to a VAC unit. Figure 5 shows the normal connec-
tions to VAC 20. These are as follows:
1
Exhaust duct.
2 Vacuum pipe from the dust collector.
3 Dirt and water separator for compressed air. The
separator is supplied with the unit.
4 6 mm (1/4”) tube airline to start-up valve. The line
is supplied with the unit.
5 Control cable for start-up valve, thermal switches
and ASC damper.
6 Optional: Control cable for when not using ASC by
PLC.
7 Motor power supply.
8 Optional: Maintenance switch. This is required in
most countries.
9 Start and control unit normally with Y/D-starting.
Direct starting is also an option.
10 Terminal box
11 Optional: ASC terminal box for when not using ASC
by PLC. Sold as an accessory.
NOTE!
Additional exhaust air ducts should be routed
straight and as short as possible. Pressure drop
for complete system shall be considered by the
installation designer or the user.
4.3 Start-up valve
Figure 6 and Figure 7 show a circuit diagram for the
control of the start-up valve. The solenoid valve V1
is engaged only after the start and control unit has
switched over to D-mode. The valve needs com-
pressed air to work. See the start- and control unit's
wiring diagram for connecting the start-up valve.
4.4 Flow restrictor FR 160
A flow restrictor, FR 160, is mounted close to the fan
outlet on most VAC 20 units, see
Figure 4 . The re-
strictor protects the motor from overloading by gradu-
ally closing a valve restricting the airflow.
The flow restrictor is fully mechanical. It consists of
a valve blade, Item 1, welded to a shaft, Item 3. The
shaft turns in ball bearings fitted to the housing, Item
2. The spring, Item 6, holds the blade in the normally
open position.
The spring keeps the blade fully open when the flow
is lower than the restrictor setting point. At the set-
ting point, the blade starts turning and closes more
and more as the flow increases. This result in a flow
restricted to a value corresponding to the nominal mo-
tor power. The spring is correctly adjusted before de-
livery of the unit. See
Chapter 8 Maintenance for read-
justment of the spring (if necessary).
The flow restrictor is fitted with a damper, see Fig-
ure 4 Item 4, to prevent the flow restrictor from self-
oscillating. It consists of a cylinder filled with oil. In the
cylinder, a piston moves freely. The damper only af-
fects rapid movements that could cause self-oscil-
lating. Rapid movements are hindered by the oil that
must pass by the piston in a small gap between the
piston and the cylinder wall.
4.5 Anti-surge control
Figure 13 shows the main components of the anti-
surge control. These are as follows:
1
Silencer
2 Valve TVS 76
3 Control motor. 24 V AC.
4 Cable
5 Optional: Current transformer. 100/1 A
6 Optional: Universal relay. 24 V AC.
7 Optional: Current sensing relay, 2 units MAX and
MIN. 24 V AC.
VAC versions' which anti-surge control is controlled
by, the start and control unit does not have compon-
ents 5, 6 or 7.
4.6 Bearing temperature switches
The circuit trips at temperatures over 110°C (230°F)
and the unit are stopped. Thermal tripping results in
an error indication in the starting equipment.
Figure 6
and Figure 7 show a circuit diagram for the overheat-
ing cut-out for the bearings on VAC 20. The circuit in
the start and control unit must require a manual reset.
The voltage must not exceed 24 V.
EN
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