The
models PAC-30U and PDC-30 proximity switches are solid state
point level devices used to detect the absence or presence
of bulk solids. The compact configuration makes this product
ideal for tight spaces or low cost level detection. As material
comes in contact with, or in close proximity to, the PAC-30U
or PDC-30, an internal solid state switch is activated. The
PAC-30U is AC operated (20-265 VAC) and is universal in that
it is switch selectable for either normally open or normally
closed operation. The PDC-30 is DC operated (10-40 VDC) and
is available in either PNP or NPN configuration, each of
which can be wired in either a normally open or normally
closed operation mode.
The
PAC-30U and PDC-30 are RF capacitance-type level controls,
which operate by detecting the electrical effect of the surrounding
material such as air, plastic pellets or powders. A radio
frequency is applied to the proximity switch sensing region
and is continually analyzed to determine the influence of
the surrounding environment. Since all materials have dielectric
constants and conductance values that are different from
that of air, the resultant impedance seen by the radio frequency
changes whenever material approaches or contacts the sensing
region. This influence is measured within the circuitry and
compared with the reference point set by the sensitivity
adjustment, which determines how much influence must be present
before the output changes.
Specifications
Model
PAC-30U:
Housing:
Thermoplastic
Polyester
Enclosure
Protection:
IP67
(NEMA 4 equivalent)
Power
Requirements:
20-265
VAC, 45-65 Hz
Mounting
Thread Size:
M30
x 1.5
Sensing
Distance:
4
to 25 mm adjustable
Indicator:
LED,
yellow
Output:
Normally
Closed or Normally Open, Switch Selectable
Leakage
Current:
<2.5
mA
Load
Current:
10-500
mA
Frequency
of Operating Cycle:
25
Hz
Operating
Temperature:
-13° to
176° F (-25° to 80° C)
Electrical
Connections:
Cable,
6ft(1.8m), 18-20 AWG
Approvals:
UL/CSA
General Purpose; CE Mark
Model PDC-30:
Housing:
Thermoplastic Polyester
Enclosure Protection:
IP67 (NEMA 4 equivalent)
Power Requirements:
10-40 VDC
Mounting Thread Size:
M30 x 1.5
Sensing Distance:
4 to 25 mm adjustable
Indicator:
LED, yellow
Output:
13-8231, NPN (sinking)
13-8241, PNP (sourcing)
Consumption:
<10.0 mA
Load Current:
0-200 mA
Frequency of Operating Cycle:
100 Hz
Operating Temperature:
–13° to 176° F (-25° to 80° C)
Electrical Connections:
Cable, 6ft(1.8m), 18-20 AWG
Approvals:
CE Mark
Warranty
Monitor
Technologies warrants each proximity switch it manufactures
to be free from defects in material and workmanship under
normal use and service within two (2) years from the date
of purchase. The purchaser must give notify Monitor of any
defects within the warranty period, return the product intact,
and prepay transportation charges. The obligation of Monitor
Technologies LLC under this warranty is limited to repair
or replacement at its factory. This warranty does not apply
to any product which is repaired or altered outside of Monitor
Technologies' factory, or which has been subject to misuse,
negligence, accident, incorrect wiring by others, or improper
installation.
453A.4.0407
Global Flour Processor Uses Flexar® Guided Wave Radar
A large global flour processor and food products company recently began using the Flexar® guided wave radar in a total of eighteen (18) silos and bins to manage their finished product inventory. Readings from these continuous level sensors is reported as being reliable and accurate, even during pneumatic filling, contrary to their previous measuring system. A previous non-performing ultrasonic system was replaced by the Flexar level sensors. Flexar guided wave radar level sensors were chosen as the best for pneumatically filled dust laden flour silos.
Eight (8) Flexar level sensors are installed in load-out silos that fill bulk trucks with processed and finished flour. These silos are 12ft in diameter and 35ft tall. The finished flour is pneumatically conveyed into these silos. During filling the internal environment of the silos is very dusty and turbulent. The finished flour in these silos is used for loading bulk transport trucks for distribution. In addition, ten (10) Flexar level sensors are installed in 40ft high bins that contain bran. This material is also sent by bulk transport to end users.
All of the Flexar level sensors are equipped with an RS485 digital communications output that is connected to a PC with a graphical user interface for inventory management purposes. Monitor’s SiloTrack™ inventory management software is used by the facility to monitor and manage material inventories of both the finished flour and the bran. SiloTrack allows for multiple user viewing and data access via LAN and this is how the facility will be using the software that provides a flexible, graphical user interface, alarms, report generation and history analysis functions.
Guided wave radar is especially well suited to level measurement applications of dusty powder materials even when measuring during pneumatic filling. Flexar guided wave radar utilizes TDR (time domain reflectometry) technology. Radar pulses are continuously transmitted down the sensor’s probe and guided to the material surface where they are reflected back to the electronics along the wave guide. The time-of-flight of the pulses is measured and directly related to the distance to the material surface and its level.
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