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NHR-XTRM temperature remote transmission monitor

user's manual

Product introduction

         NHR-XTRM temperature remote transmission monitor adopts advanced microprocessor for intelligent control. It is suitable for the display control of temperature physical quantity detection signal, and it can patrol and detect multiple measurement signals. And can perform a high-precision linear correction on a variety of non-linear input signals. The control output has remote transmission output; the highest measurement point after multiple comparisons is used as the output (remote transmission output). The output circuits are all optically isolated and have good anti-interference ability. With high brightness LCD liquid crystal display. The shell is made of aluminum alloy, and the whole machine adopts a wall-mounted structure (width × height × depth = 110 × 160 × 60mm ), which is very easy to install.

    This product can measure 2 to 4 measurement points at the same time , and after comparing the temperature in each temperature measurement circuit, take one point of the highest temperature as the output, and you can watch the temperature of each point one by one at the scene by pressing the button.

Technical parameters

Product use

1. Oil temperature of rotary kiln supporting wheel

2 , the pinion kiln oil tank

3 , the temperature of raw material import and export bearing

4. Ash hopper temperature of coal dust collector

5 , pulverized coal box temperature

6 , the temperature of the main motor winding of the raw material mill

7 , the temperature of the main motor bearing of the raw material mill

8. Stator temperature of raw material exhaust fan motor

9 , high temperature fan winding temperature

10 , high temperature fan bearing temperature

Product selection

Five, electrical connection

The connection between the instrument and external PT100 thermal resistance should be performed after opening the instrument cover, and the PT100 thermal resistance is connected. Indicating instruments, recording instruments, regulators, etc. can be connected in series with the power supply in the output circuit. The output current is proportional to the change in temperature, but independent of the change in power supply. Its application principle is shown in the following figure:

      The measurement signal of the self-resistance sensor is amplified by a preamplifier, and then selected by a comparison input circuit (high-temperature signal selection) or a point selection input circuit. This signal changes the output voltage of the amplifier through a current ( V / I ) conversion unit. For 4-20mA constant current output, the schematic block diagram is shown below: 

Six, instrument use instructions

It needs to warm up for 10 minutes after turning on the instrument. The installation of the instrument should be as close to the measurement point as possible, so that the following advantages of the two-wire system can be fully utilized:

1. High anti-interference ability, because the signal is transmitted at a high level, which can suppress noise and interference.

2. Simple wiring, that is, the instrument can be connected with twisted pair wires from the field control room, which reduces the cost of wiring.

Input thermal resistance, in order to avoid measurement errors, the lead resistance of the sensor must be guaranteed a certain value, where for each Pt100 sensor, fixed to the lead resistance 0.35 [Omega], 0.35 [Omega] of the corresponding conductor section and length are as follows:

      Any cross-section wire can be used, but the total lead resistance must be 0.35 Ω. Otherwise, lead error will occur. For example, every 0.38 Ω change in lead resistance will cause a temperature error of 1 ° C. When the input uses a thermocouple, the connection between the input terminal and the thermocouple must use the corresponding compensation wire, and the lead of the input terminal must consider the shielding of the external magnetic field.

    The size of the load resistance RL of the meter depends on the display mode of the meter. The size of the power supply voltage and the power supply ripple VR is related to whether input / output isolation is used.

    3. For a circuit that is not used temporarily, the input termination is less than 100 Ω or the input wire is shorted. If the input open-circuit meter does not work properly, the display on the LCD panel shows as .

    4. Under normal operating conditions, the meter measures the temperature of four channels at the same time, but only displays and outputs the signal with the highest temperature.

Seven, instrument maintenance and adjustment

      Because the long-term stability of the meter has been considered in the design, and the meter has undergone long-term aging and calibration before leaving the factory, no special maintenance is generally required under normal use conditions. If experience proves that the instrument is faulty, it can be sent to our company for repair. The company implements life-long maintenance on this series of products.

    If it is found that the meter can no longer work normally, the output current of the meter exceeds 20mA . In most cases, it is caused by the open circuit of the sensor, or it may be caused by the decrease of the insulation resistance between the sensor and the protective sleeve (isolated instruments can prevent this failure).

    If one input is short-circuited, it will not affect the operation of the meter. When the key is used to select this circuit, the output current is less than 4mA , and the meter head displays below zero.

Instrument adjustment steps:

    The meter error needs to be corrected when the meter is periodically calibrated. It can be adjusted according to the following steps: (Take four-circuit Pt100 input range 0 to 150 ℃ as an example)

    1. Open the instrument panel and connect the power according to the figure. First connect a standard resistance box to the input terminal of the first circuit and adjust it to 100 Ω, and short circuit the input terminals of the other circuits.

    2. Adjust potentiometer left 1 so that the output is 4mA and then set the resistance to 157.31 Ω, then adjust potentiometer left 2 so that the output is 20mA . This step is repeated many times until the satisfactory accuracy range is reached.

    3. Connect the standard resistance box to the second circuit. Use the method in step 2 to adjust the left and right potentiometers 3 and 4 of the full-scale potentiometer to make the output 4mA and 20mA respectively . When adjusting the second circuit, the remaining inputs The circuit should also be shorted.

    4. Connect the standard resistance box to the third and fourth circuits, and repeat step 2 . Adjust the potentiometer's right four, right three, right two, and right one respectively, then all four circuits are adjusted. (The inputs of non-regulating circuits should be shorted)