Gardner Denver VST225, Инструкция по установке, эксплуатации и обслуживанию

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13-17-609 Page 33
4-4
Fan VFD and Motors (Air-cooled module only)
- The radial fan providing cooling air for the heat
exchangers is driven by an inverter-duty (TEFC) electric motor, which in turn is energized by a pulse-
width modulated, variable frequency drive (commonly referred to as VFD). This combination of
components enables the controller to match the heat exchanger coolant needs in proportion with load
level (e.g., flow capacity) of the compressor package, thus saving fan power. The AirSmart controller
supplies the operational logic, which governs the fan drive and motor combination and it is based on
proportioning the fan speed to that of the 1st stage compressor.
The drive includes adequate current overload protection for its companion motor, and is designed to
operate with 3ph-60Hz-460vac electrical power. The electrical power wiring and communications cable
must be provided at the side
– see Sec 6, page 49 for details.
Ventilation Fan Motors and Starter – Combination fan/motors exhausts hot air build-up from the
package enclosure and the electrical enclosure. The starter provides control and overload protection for
all three (3) ventilation fan/motor. Overload heaters should be selected and adjusted based on the
aggregate motor nameplate amps and the instructions located inside the cover of the electrical box. This
device is designed to operate with 3 ph-60 Hz-460 vac electrical power
– the necessary electrical wiring
has been provided.
Control Transformer
- This device reduces the incoming power voltage on electrical services other than
the standard 460 vac. When included in package hardware, two primary fuses and one secondary fuse
are provided for overload protection.
Power Supply (24Vdc)
- This device supplies electrical power to the AirSmart controller and various
solenoid valves.
For Letter References A thru AA below, see Figure 4-3, page 35.
Inlet (Butterfly) Valve (B) – This device is located at the intake flange of the 1st stage compressor. A
spring-loaded pneumatic cylinder actuates the valve. During compressor operation (at least 5 Hz 1st
stage compressor shaft speed), an air pressure signal (60 psig min) directed to the actuator overcomes
the internal spring load and opens the valve. During stopped operation modes (e.g., commanded from
keypad or initiated by protective shutdown), the air signal is vented and the spring load closes the valve.
This prevents trapped air and oil from exiting through the inlet filter. The pneumatic actuator has a
maximum operating pressure of 125 psig. See Letter Reference Q below.
Minimum Discharge Pressure/Check Valve (G) –
This device maintains a minimum pressure within the
air/oil reservoir, thus insuring (cooling/lubricating) oil injection flow into the compressors. It also serves as
a check valve to prevent back flow of compressed air from the customer
’s piping back into the
compressor package when it is not active.
The spring-loaded piston does not allow the discharge of compressed air from the air/oil reservoir until the
compressor builds up pressure beyond 80 psig. Beyond this pressure level, the valve remains fully open.
Oil Mixing Valve (L) – This device, which is located at the inlet side of the oil cooler, mixes cooled and
hot oil prior to delivery to the oil filter and oil injection manifold. It helps maintain a minimum oil
temperature of approximately 140
°
F at low load levels or low ambient temperature conditions.
Pressure Relief Valve (O) – This device protects the pressure containing components of the compressor
package against high pressure exceeding 200 psig.
Check Valve – Inter-stage Pressure (P) – This device protects the 1st stage compressor and the inter-
stage piping from high pressure caused by the accidental stoppage of the 2nd stage compressor. A
build-up of inter-stage pressure is safely vented through the check valve, to the air/oil reservoir.
Pressure Regulator (Q) – This device supplies the air pressure signal to actuate the inlet control valve.
The regulator is provided with a pressure gauge and is typically set to 80 psig.