MICROWAVE 320

MICROWAVE 320
MICROWAVE 320
DATA SHEET
Position & Level
Control
R
FM
APPROVED
Approved with MT 851/MR 851 Sensors
FUNCTION
PRIMARY AREAS OF APPLICATION
Severe Environments
Where the environment is too hostile to permit reliable
operation of photo-electric controls. Microwave 320
is unaffected by dust, smoke, fog or vibration.
Single Point Switch for on-off control of bulk solids
and liquids. ON-OFF Switch presence/absence,
indication of objects.
TYPICAL USES
High Temperature Environments
Model MT 861 and MR 861 transmitters and
receivers are designed for high temperature service.
Please note: These sensors are water cooled to
maintain an operating temperature of +140°F (+60°C)
or less at the pre-amplifier.
High Level Alarm or Control
Plugged Chute Detection
Truck and RR Car Position
Flow/NoFlow Sensing of Bulk Materials in Chutes,
on Conveyors
Abrasive Materials
Eg: Crushed coal, sand, ore. Rugged construction.
No moving parts. Sensors do not protrude into flow
stream.
Corrosive - Liquid Products
Eg: Water, acids, diluted acids (within the limits
of transmitter and receiver housing and insulation
materials), water with impurities.
Liquids - Interface
Eg: Petroleum products and water.
Liquids - With Solids
Eg: Municipal waste (sewage).
1
FEATURES
Approved
All Microwave Type 1 Controls comply with FCC
rules Part 15 and are approved by the FCC as
being suitable for industrial applications. These
controls have an average power density of 0.1
mw/cm2 at the antenna, well below OSHA
guidelines. No licenses or approvals required
to use the controls.
Non-Contact
Sensor does not contact subject when used as
a position indicator control.
No Vessel Openings
Sensors can see through most non-metallic
vessels.
Non-Intrusive
When the Microwave 320 is used for level
control, transmitter or receiver sensors do not
protrude into vessel so bridging cannot occur.
Independent Time Delays
Standard, for smooth, chatter-free performance.
Field adjustable.
Corrosion Resistant, Watertight
Remote Enclosure
Glass-reinforced polyester enclosure features
captive hardware and stainless steel trim to
endure the most corrosive environments.
Versatile Power Supply
The standard unit accepts 120 Volts AC,
240 Volts AC or low voltage 24 DC input.
Long Cables
Pre-amplifiers are located at transmitter and
receiver permit use of long cable lengths up to
1,000 feet (340.8m).
Fail-Safe
A simple field selectable slide switch determines
the high or low fail-safe mode.
PRINCIPLE OF OPERATION
These controls are non-contact sensing microwave based
controls. The transmitter (source) consists basically of a
power supply, pulse modulator, Gunn oscillator, and directional
antenna. The receiver consists of a directional antenna, a
microwave mixer cavity with a Schottky barrier diode detector, a
high gain, low noise amplifier, a pulse coding network, a voltage
comparator circuit and a relay driver circuit.
In the transmitter, power is converted to a well regulated and
filtered 12 Volts DC supply. It is then pulsed at about 1 kHz by
the pulse modulator circuit. This circuit is included to permit
pulse discrimination circuitry to be used. In addition, pulsing
at a 10% duty cycle safely permits peak transmitted power
levels 10 times greater than permitted under continuous wave
operation. The pulsed DC is fed to a Gunn oscillator in the
antenna assembly, where the 12 Volts DC 1 kHz square wave
is converted to a pulsed X bank (10.525 gHz) microwave signal.
The signal is radiated by the directional antenna, which is
typically a 10dB gain horn with a beam spread of approximately
40°.
In the receiver, the signal is received by a directional antenna
and coupled to a mixer cavity containing a Schottky detector
diode. This diode converts the low level microwave signal to a
low level pulsed DC, which is then amplified by an adjustable
gain — low noise IC amplifier to a 0-10 Volts DC control
signal. This system is interconnected and uses pulse
discrimination coding. In these systems the receiver is on only
when the transmitter is on, thus the system is virtually immune
to false triggering from stray microwave interference. The level
of the amplified received signal (0-10 Volts DC) is compared
with a preset value in a voltage comparator circuit. When the
signal received exceeds the comparator set-point, an output
signal in initiated which is processed through time delay circuits
to drive the output relay.
A microwave system has been described in the above, based
on a fixed power transmitter and a receiver/detector with
adjustable gain to discriminate between various signal power
levels received at its antenna. Materials in the industrial
environment have various effects of microwave signals. For
example, low level microwaves cannot penetrate metals, but
are reflected by them. They are absorbed almost entirely by
water, and to varying degrees by water based solutions or
products that have a significant moisture content such as grain,
wood products, etc.
Transmission losses increase with increasing dielectric
constants and increase with increasing conductivity. For
example, air (dielectric constant of 1 and conductivity of zero)
transmits microwave with no loss while sea water (dielectric
constant of 55 at X-band and conductivity of 4 mhos/meter)
provides extreme attenuation of the microwave energy. It is the
material’s dielectric constant and conductivity that determine
whether or not the material is a good candidate for microwave
control.
2
TYPICAL APPLICATIONS
SPECIFICATIONS
Level Control
Level control of liquids or solids in tanks, bins, hoppers
or chutes are some typical applications. Nonconductive-fiberglass tanks represent minimal losses to
X-based microwaves. Sensors are mounted on the
outside, opposite one another on the tank. Losses
through the tank walls and air or vapors above the
product are low. When the product level reaches the
control position, the signal is attenuated significantly,
causing the output relay to change state. Metal tanks
or hoppers must have a “window” transparent to
micro-wave signals. Sightglasses (3”-4” dia.) can
be used on liquid storage tanks, compatible with the
pressures, temperatures and chemical properties of
the materials stored in the tank. For metal vessels
storing solid materials, “windows” can be constructed
of materials such as high density polyethylene or
other similar substances compatible with the produce
contained therein. A partial list of materials low in loss are
below. These are potential candidates for windows.
Input Voltage
NOMINAL
115 Volts AC
230 Volts AC
24 Volts DC
Power
5 volt-amperes
Frequency
50-60 Hz
Time Delay
Independent with auto reset
on make, or break
Delay Time Range
50 minimum - 10 second nominal
30 second maximum
ABSOLUTE LIMITS
95-135 Volts AC
190-270 Volts AC
±4 Volts
Fail-Safe
High Level or Low Level —
Switch Selectable
High Level Fail-Safe Position:
Relay is de-energized when
material is present
Low Level Fail-safe Position:
Relay is de-energized when
no material is present
Indicators
Two, light emitting diodes (LED)
RED - illuminated when material is
not present at sensor—path is complete
YELLOW - illuminated when relay is
energized
TYPICAL WINDOW MATERIALS
Operating Temperature -40°F to +160°F
(Amplifier)
(-40°C to +71°C)
Fiberglass
Output
Relay, DPDT Form C
Ratings
5 amp @ 120 Volts AC resistive
3 amp @ 240 Volts AC resistive
3 amp @ 24 Volts DC resistive
Glass (no lead)
Lexan®
Lucite®
Operating Temperature
(Transmitter/Receivers) See Page 26 for details.
Magnesium Firebrick
Mica
Nylon
Paraffin
Plexiglass
Polyethylene
Polystyrene
PVC
Quartz
Styrofoam
Teflon
3
SENSORS (Transmitters & Receivers)
Sensor & Model No.
Description
Long range transmitting/receiving
sensors with 10db gain home antennas
Maximum range 100´ in air.
NEMA 4x enclosures, MT801/MR801
temperature range: -20°F to +140°F
(-30°C to +60°C).
Typical Applications
Standard Service
Vehicle detection, railroad car
detection & positioning.
Liquid level control, bin level
control (sand, rock, asphalt,
coal, cement, fly ash, etc.) Use with Part #41121 window.
MT801/MR801
Short range accurate high/low level
detection. Range up to 10´ in air.
Used primarily for accurate position
and level sensing of bottles, small
boxes, etc. NEMA 12 enclosures.
Temperatures range: -20°F to +140°F
(-30°C to +60°C).
High/low level detection, empty
bottle detection, battery filling level
control, empty box detection
counting, short range plugged
chute.
Similar to MT811/MR811 except
10 db gain horn antennas are used.
Designed to be used in Part No.
41105-X, waveguide extension kit.
Maximum range 100´ in air,
Enclosures is NEMA 12. When used
with 41105-X, maximum temperature
at antenna is 600°F (313°C).
Amplifier maximum temperature is
140°F (60°C)
Waveguide with 10 db gain horn
antenna. Level control when vessel
or environment is extremely hot.
Furnaces, kilns, cupolas, fly ash,
furnace fluidized beds, etc. Use
with Part #41121, #41213 and with
castable refractory materials.
Identical to MT801/MR801 except
sensors are constructed in 2 1/2”
steel pipe. Designed to be screwed
directly into steel vessels using 2 1/2”
weldment (P/N41249-order separately).
Window material is FDA approved
UHMW polyethylene 1” thick.
Contact factory for other available
material. Temperature range:
-20°F to +140°F (-30°C to +60°C).
Severe service.
Bin level control of sand, rock,
asphalt, coal, etc. In areas where
physical abuse of sensor is
possible. Rugged.
MT811/MR811
MT841/MR841
MT851/MR851
R
FM
APPROVED APPROVED
Class II, Div 1, Groups E, F, G Similar to MT851 and MR851 except
waveguide 10db horn and electronics
is located inside water cooled jacket.
MT861/MR861
4
Hot product, water cooled Level
control of limestone, ores and
other products contained in
firebrick enclosures.
ACCESSORIES
(Mounting)
Part No. 43681
Part No. 41347
Microwave Firebric Window Assembly
Mounting Support Plate for MT/MR801,
MT/MR811, MT/MR841 systems.
Part No. 41121
Part No. 41249-2
Microwave UHMW Polyethylene,
Lexan® or Teflon® Window use
with MT/MR801, MT/MR811,
and MT/MR841 systems.
Weldment for MT/MR851.
Part No. 41213
High Temperature Glass Window for use and
Weldment with MT/MR841 and MT/MR811.
Maximum Ratings: 860°F; 500°F (260°C) @ 0 PSI;
70°F (21°C) @ 450 PSI.
ACCESSORY ITEMS
In certain cases it may be necessary to “pipe” waveguide around existing obstructions, extensions and elbows are available.
Part No. 41361 90°
Part No. 41105-X
Right Angle Waveguide “E BEND”
(includes mounting hardware)
Waveguide Extension Kit
(includes mounting hardware)
Part No. 41524 90°
Right Angle Waveguide “H BEND”
(includes mounting hardware)
CABLE ASSEMBLIES
Part No.
Type
Description
17102
General Purpose
50 ft. (16 meters).
2 Conductor Shielded PVC Jacketed Cable
Temp Range -40°F to +160°F (-40°C to +70°C)
42564
General Purpose
100 ft. (33 meters).
2 Conductor Shielded PVC Jacketed Cable
Temp Range -40°F to +160°F (-40°C to +70°C)
17198
High Temperature
2 Conductor Shielded Teflon® Jacketed Cable
Temp Range -40°F to +400°F (-40°C to +204°C)
5
TIME DELAY SETTINGS
Bin Level Control
Normally requires both time delays to insure that
a turbulence upper level will not cause a false trip.
Clockwise rotation of Beam Make and Beam Break
increases time delay.
ORDERING INFORMATION
MICROWAVE
320- _____ - _____ - _____ - _____ - _____
Approval
00 = Standard
AUS = Australian C-Tick
Plugged Chute Control
Applications will normally have delay on Beam
Break so that falling material will not trip the control
relay prematurely.
Interconnect Cable
P50 =Pair of 50 ft. PVC Cables,
2 Conductor
P100=Pair of 100 ft. PVC Cables,
2 Conductor
B
=Bulk PVC Cable, 2 Conductor
(Lengths over 100 ft.)
T
=Bulk Teflon Cable, High Temp
(300 ft. or Less)
00 =None
Starvation Control
Applications require delay on Beam Make so that
when product ceases to flow (starvation) the relay
will not operate until some reasonable time period
has elapsed. This prevents false signals due to
temporary reduction in flow.
Mounting Options (priced per pair)
W =Standard, 2-1/ 2” C.S. Weldment for 851’s
U =4” C.S. Weldment and UHMW Window
T =4” C.S. Weldment and Teflon Window
F =4” C.S. Weldment and Firebrick
(750° F max)
G =2” Weldment and Quartz Glass Window
(400° F max)
H =High Temp, 4” Lagging Extension for 851’s
A =High Temp, Angled Weldment for
Fly Ash Applications
E =High Temp, 12” Lagging Extension for
Fly Ash Bracket
00=None
Object Detection Control
Such as vehicle washing equipment require about
1/2 second delay on Beam Make and Beam Break
to prevent false signals.
General Comments
Always use as much time delay as the application
will permit. These time delay adjustments permit
custom application of the Microwave 320 System
to your specific process needs.
R
FM
APPROVED
Sensor Type (priced per pair)
851 = Standard, C.S. Direct Coupled, 2-1/ 2” NPT
811 = NEMA 12, 3.9” x 3.8” x 6.6” Enclosure
with Extension
801 = NEMA 4X, 3.9” x 3.8” x 6.6” Enclosure
861 = High Temp, Water-Cooled (750°F max)
851S= 316 Stainless Steel, Direct Coupled, 2-1/ 2” NPT
851V= Vibration Resistant 851’s
841 = NEMA 12, 3.9” x 3.8” x 6.6” Enclosure
with Extension and Horn
CSA APPROVED WITH
MT/MR 851 SENSORS FOR
Class II, Division 1 —
Groups E, F & G hazardous locations.
FM APPROVED WITH
MT/MR 851 SENSORS AS
DUST IGNITION PROOF FOR
Class II, Division 1 —
Groups E, F & G hazardous locations.
Note:801, 811, 841, 851, 851S, 851V —
140° F max for Electronics
Enclosure Type
S =Standard, NEMA 4X Enclosure
C=Clear NEMA 4X Enclosure
O=OEM, Electronic Assembly with Mounting Hardware
(No Enclosure)
T =Standard, NEMA 4X Enclosure, Test Switch
D=Clear, NEMA 4X Enclosure, Test Switch
C-TICK APPROVED WITH
Model Microwave 320 Point Level Switch
An
Process Instrumentation
Company
5911 Butterfield Road
Hillside, IL 60162
Ph: (708) 236-6000
Fax: (708) 236-6006
Email:sales@ljtechnologies.com
6
PDS-D320-1C
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertising