FT8051 series RF admittance continuous level meter

The FT8051 series is a universal RF admittance continuous level instrument suitable for most applications. The instrument consists of an electronic unit and rod or cable type sensing elements. The sensors can be made of various materials and can be installed as a whole or separately. Used for continuous measurement.

　　measuring principle

Radio frequency admittance level control technology is a level control technology developed from capacitive level control technology, which has better anti hanging material performance, more reliable operation, more accurate measurement, and wider applicability. The meaning of "admittance" in "radio frequency admittance" is the reciprocal of impedance in electricity, which is composed of resistive, capacitive, and inductive components. "Radio frequency" refers to high-frequency radio waves, so radio frequency admittance technology can be understood as measuring admittance with high-frequency current. A high-frequency sine oscillator outputs a stable measurement signal source, utilizing the principle of a bridge to accurately measure the admittance of sensors installed in the container under test. In direct action mode, the output of the instrument increases with the rise of the material level.

The difference between radio frequency admittance technology and traditional capacitance technology lies in the diversity of measurement parameters, three terminal drive shielding technology, and the addition of two important circuits, which are improved based on valuable experience in practice. The above technology not only solves the problems of cable shielding and temperature drift, but also solves the problem of hanging materials at the root of vertically installed sensors.

For a container made of highly conductive material, since the material is conductive, the grounding point can be considered to be on the surface of the sensor insulation layer. For instrument sensors, it only appears as a pure capacitor. As the container is discharged, there is a hanging material on the sensor, which has impedance. In this way, the previous pure capacitor has now become a complex impedance composed of capacitors and resistors, causing two problems.

The first issue is that the material itself is equivalent to a capacitor to the sensor, which does not consume the energy of the transmitter (pure capacitor does not consume energy). However, if the equivalent circuit of the hanging material to the sensor contains a resistor, the impedance of the hanging material will consume energy, thereby pulling down the oscillator voltage and causing changes in the bridge output, resulting in measurement errors. We have added a driver between the oscillator and the bridge to replenish the consumed energy, thus stabilizing the oscillation voltage applied to the sensor.

The second issue is that for conductive materials, the grounding point on the surface of the sensor insulation layer covers the entire material and hanging area, allowing the effective measurement capacitance to extend to the top of the hanging area, resulting in hanging errors, and the stronger the conductivity, the greater the error.

But no material is completely conductive. From an electrical perspective, the hanging material layer is equivalent to a resistor, and the part of the sensor covered by the hanging material is equivalent to a transmission line composed of countless infinitely small capacitors and resistance elements. According to mathematical theory, if the hanging material is long enough, the impedance and reactance values of the capacitance and resistance parts of the hanging material are equal. Therefore, an AC phase detector sampler can be used to measure capacitance and resistance separately. The measured total capacitance is equivalent to the C level+C hanging material, and subtracting the resistance R equal to the C hanging material can obtain the true value of the level, thereby eliminating the influence of hanging material.

　　characteristic

Intrinsic safety design: Two wire intrinsic safety design, where both the unit and probe are inherently safe

Maintenance free: No moving parts, no wear or damage, no need for regular cleaning, no need for repeated debugging

Anti hanging material: The Drive shield electrical design allows it to ignore the influence of hanging materials on walls or sensing components

No drift: Will not drift due to temperature or density changes in the medium

Reliable lifespan: Unique technology ensures instrument service life of up to 15 years

Safety protection: Built in probe input device, strong protection ability, not easily affected or damaged by static electricity, impact and electrochemical phenomena

　　Typical applications

Water level detection of deep water wells in oil fields

Groundwater level measurement and environmental protection testing around cities

Water level detection of power plant water source well

Water level detection of deep water wells in water plants

　　performance index

Measurement equipment level: CAT I level, transient rated voltage 1500V, cannot be used for levels other than CAT I level

Output: 4-20mA

Measurement method: can be set as level mode (DIR) or distance mode (REV)

Power supply: 15-35VDC

Power: less than 0.5W

Accuracy: ± 1%

Temperature effect: 0.25%/10 ℃ (18 ℉)

Load resistance: Output circuit load resistance capacity of 450 Ω at 24VDC

Environmental temperature: T5: -40 to+70 ℃ (-40 to 158 ℉); T6: -40 to+60 ℃ (-40 to 140 ℉) (The influence of medium temperature on ambient temperature cannot exceed the instrument's requirements for ambient temperature)

Response time:<0.5 seconds

Delay: adjustable from 0.5 to 80 seconds

Electrostatic spark protection (for sensors): anti surge impact 1000V, anti-static 4kV/8kV

RF protection (built-in filter): The whole machine is tested by injecting current through a 10V/m electromagnetic field and a 3V/m electromagnetic field in space

Measurement depth: up to 1000 meters (range 0-180 meters)

Cable length: 5m (standard) (197 "), 0.1 (3.9") to 50m (1968.5 ") (optional)

Consult the manufacturer for 50m (1968.5 ") to 100m (3937")

Electrical interface: M20 × 1.5 (optional 3/4 "NPT)

Process connection: NPT thread installation (standard, optional BSPT), flange installation (optional)

Process temperature: -20 to+120 ℃ (-4 to 248 ℉)

Process pressure: ≤ 1.6MPa (232psi)

Probe material: 304SS/PVDF

Shell material: die cast aluminum with epoxy coating

Shell protection: Compliant with IP67 protection standard

Explosion proof grade: ExiaICT4

Certification: PCEC/NEMSI. For other certifications, please consult the manufacturer

Wiring diagram of deep well water level gauge system

The FT8051 series deep well water level gauge belongs to the intrinsic safety type instrument. Whether installed as a whole or separately, when installed in hazardous environments, a jointly certified safety barrier needs to be added to its power supply circuit. Both single and double barriers can be used, but the connection method is different. The examples in the intrinsic safety application system and safety barrier wiring diagram are single barrier integral installation and double barrier separate installation. For safety barrier products that have been jointly certified, please consult our company or our agent. The maximum impedance of cables, loads, and safety barriers under 24VDC power supply is 450 Ω.

Please refer to the instructions for the use of safety barriers for grounding requirements.

The requirements for safety barriers in this level gauge are:

Uo=28VDC

Io=93mA

Po=0.65W

Co=0.083uF

Lo=4.2mH

Safety parameters of this instrument:

Ui=30V

Ii=100mA

Pi=0.75W

Ci=6nF

Li=240uH

Intrinsically safe application system and safety barrier wiring diagram

　　Installation requirements for deep well water level gauge

The installation requirements for the FT8051 series RF admittance deep well water level measurement system are as follows:

Measure the length of the well pump tube and make a record to ensure that the sensor enters the wellbore at the correct length.

When lowering the pump, use insulated wire to tie and fix the sensor heavy hammer to the upper part of the pump body about 30 centimeters above the pumping point.

The sensor enters the wellbore with the pump tube and is tied to each section of the pump tube to minimize the binding points between the sensor and the pump tube. The sensor should be kept parallel to the pump tube and should not be rotated or twisted to avoid measurement errors.

Instruments installed according to intrinsic safety requirements must comply with relevant national laws and regulations. It is particularly important to note that each circuit must be equipped with a certified safety barrier, and the instruments must be grounded well and reliably as required. Please consult our company or our agent for certified safety barrier products.

The ripple of 24VDC power supply shall not exceed 100mV. The power ground wire should be connected to the standard ground or standard instrument ground, and cannot be connected to the power ground. Shielded cables are recommended for on-site power cables, and long-distance unshielded cables should not be parallel to AC power cables. The cable passing through the area requires lightning protection devices to prevent lightning strikes.

The power cable is an armored explosion-proof 3-core cable with an outer diameter of no more than 12mm. The cable conductor material is copper with a cross-sectional area of 0.13-2.1mm2 (AWG14-26). The cable insulation strength is 1500V and meets the requirements of IEC60245/60227 standard. The switch used complies with the requirements of IEC60947 standard.

Please pay attention to protecting the threads and seals of the explosion-proof housing of the instrument during installation, to avoid scratches and foreign objects such as sand adhering to the threads.

AOR3000B series paperless recorder (optional)

AOR3000B series monochrome (blue screen, yellow screen) paperless recorder has 16 analog inputs, up to 4 analog outputs, 16 alarm outputs (configurable), PID control algorithm and other functions

　　Functional Features

160 * 128 dot matrix, optional high brightness yellow background black text, high brightness blue background white text LCD screen, LED backlight, clear image;

High speed, high-performance microprocessor that can simultaneously detect, record, display, and alarm 16 signals;

Large capacity FLASH flash memory chips store historical data and never lose data in case of power failure; Depending on the recording interval, data from XX hours to XXX days can be stored

The numerical range for displaying engineering quantity data is wider, and can display 5-digit values: -19999 to 30000;

Can configure and display channel numbers, engineering units, etc;

Alarm display, indicating the lower and lower limits, lower and upper limits, and upper and upper limits of each channel alarm simultaneously;

High display accuracy: The basic error of displaying numbers, curves, and bar charts is+-0.2% FS;

Data transfer function, optional USB storage, reading and analyzing data through computer USB interface;

Standard serial communication interfaces: RS485 and RS232C;

The standard open Modbus communication protocol, in addition to our company's upper computer management software, this instrument also supports popular professional configuration software such as iFIX, Kingview, MCGS, etc;

The new switch power supply can operate normally within the range of 85VAC~265VAC of AC power supply;

Provide transmitter+24VDC power supply

Power outage protection time: Built in FLASH memory to protect parameters and historical data, which can be permanently saved after power outage. Integrated hardware clock that can operate accurately even after power failure.

　　TECHNICAL INDEX

Working power supply: 85VAC~265VAC

Display: 160 × 128 dot matrix graphic LCD display, LED backlight

Basic error:+-0.2% F.S

Input: 1-16 channels 4-20mA current input

Output: 24VDC current<200mA

1-16 configurable relay contact outputs, with a contact capacity of 1A and 250VAC (resistive load)

Upper limit, upper limit, lower limit, lower limit alarm output

1-4 4-20mA current outputs

1-4 PID outputs

Communication: RS232 or RS485

Baud rates of 1200, 2400, 9600, 57600

Storage capacity: 32Mbit, 64Mbit, 96Mbit

Record interval: 1-240 seconds optional

Record time: XX hours/pen~XXX days/pen

Data backup: 128-512M USB drive optional

Environmental temperature: T5: -40 to+70 ℃ (-40 to 158 ℉); T6: -40 to+60 ℃ (-40 to 140 ℉) (The influence of medium temperature on ambient temperature cannot exceed the instrument's requirements for ambient temperature)

Environmental humidity: 0-85% RH

Hole size: 137mm × 137mm

Dimensions: 144mm × 144mm × 180mm