DL-RZG-2100S isolator

The DL-RZG-2100S signal isolator is a signal isolation device that converts input single or dual current or voltage signals into output isolated single or dual linear current or voltage signals, and improves the electrical isolation performance between input, output, and power supply. Signals may encounter various interferences during transmission, and it is particularly important to use signal isolators to ensure signal stability.

Anti interference design of power supply systemDL-RZG-2100S isolator

The serious hazard to the normal operation of sensors and instruments is the peak pulse interference of the power grid. The electrical equipment that generates peak interference includes welding machines, large motors, controllable machines, relay contactors, inflatable lighting fixtures with ballasts, and so on. Peak interference can be suppressed using hardware, software, and/or a combination of hardware and software.

(1) There are three common methods to suppress the impact of peak interference using hardware circuits:

① Connect an interference controller designed according to the principle of spectrum equalization in series with the input end of the instrument's AC power supply, and distribute the concentrated energy of the peak voltage to different frequency bands, thereby reducing its destructive power;

② Add a super isolation transformer to the input end of the instrument's AC power supply and use the principle of ferromagnetic resonance to suppress spike pulses;

③ Connect a varistor in parallel at the input of the instrument's AC power supply, and use the decrease in resistance value when the peak pulse arrives to reduce the voltage that the instrument receives from the power supply, thereby weakening the impact of interference.

(2) Using software methods to suppress peak interferenceDL-RZG-2100S isolator

For periodic interference, programming can be used for time filtering, which means controlling the thyristor to conduct without sampling at the moment of conduction, effectively eliminating interference.

(3) Using a combination of hardware and software watchdog technology to suppress the impact of spike pulses

Software: Before the timer expires, the CPU accesses the timer once to restart the timer. The program runs normally, and the timer will not generate overflow pulses, so the watchdog will not work. Once a "flying program" occurs due to peak interference, the CPU will not access the timer before the scheduled time, resulting in a timing signal that triggers a system reset interrupt to ensure that the smart instrument returns to its normal program.

(4) Implement grouped power supply,For example, separating the driving power supply of the motor from the control power supply to prevent interference between devices.

(5) The use of noise filters can also effectively suppress the interference of AC servo drives on other devices.This measure can effectively suppress the above-mentioned interference phenomena.

Technical Features

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The signal isolator adopts advanced digital technology and has excellent performance in suppressing high and low frequency interference signals. Even in high-power variable frequency control systems, it can still be reliably applied. Internally, it adopts many advanced technologies such as digital calibration, zero free and full-scale potentiometers, automatic dynamic zero calibration, and temperature drift automatic compensation. The application of this series of technologies ensures the stability and reliability of the product scientifically.

signal isolator

Signal isolators can be used in conjunction with unit combination instruments, DCS, PLC and other systems, and are widely used in major projects in industries such as oil fields, petrochemicals, manufacturing, power, metallurgy, etc.

Technical Specifications

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◇ System transmission accuracy: ± 0.2% × F · S

◇ Temperature drift: ≤ 0.0035% F · S/℃ (35PPM/℃)

LCD digital display: dual row four digit display, floating point decimal.

signal isolator

Allowable external load impedance for current output: 0-500 Ω for 4-20mA output; When outputting 0-10mA, 0-1k Ω is required. Please specify when placing an order for a larger load capacity.

◇ Electromagnetic compatibility: Complies with the requirements for electromagnetic interference resistance of products in Class IV (harsh industrial environments) as specified in IEC61000-4-4:1995.

◇ Input/output/power/communication/dual circuit insulation strength: DC ≥ 2000V.DC, AC ≥ 1500V.DC

◇ Storage and transportation environment temperature: -40 to+80 ℃

Relative humidity: 10-90% RH (at 40 ℃)

Power supply: AC 95-265V DC 12-32V (reverse protection)

◇ Input power: 0.9-1.8W

Communication interface: RS232 or RS485, MODBUS software protocol (optional).

◇ Dimensions: Width x Height x Depth: 22.5 x 100 x 115mm

Net weight: 140g ± 20g

All features

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1、 Protect the control circuit of subordinates.

2、 Weaken the impact of environmental noise on the testing circuit.

3、 Suppress interference from public grounding, frequency converters, solenoid valves, and unknown pulses on equipment; At the same time, it has the function of limiting voltage and rated current for lower level equipment, which provides faithful protection for transmitters, instruments, frequency converters, solenoid valve PLC/DCS input and output, and communication interfaces. The DIN series rail structure is easy to install and can effectively isolate the potential between input, output, power supply, and ground. Capable of overcoming frequency converter noise and various high and low frequency pulsation interferences.

power supply method

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1. Isolator with independent power supply:

An independent DC power supply of 20-35VDC is required. The advantage of this method is high isolation transmission accuracy; The power supply, input, and output are completely isolated, and the power supply of the multi-channel system does not need to be isolated, ensuring high anti-interference performance. The input signal can be converted to other types of models.

2. Isolator for circuit power supply:

In practical industrial monitoring systems, the use of DCS, PLC, or other display instruments with card internal power supply is becoming increasingly widespread. Circuit powered isolators often cannot meet the high requirements for signal isolation and transmission accuracy of these cards, as well as the high requirements for distribution voltage of two-wire transmitters. Therefore, the output circuit power supply type isolator retains the superior performance of the independent power supply type isolator while meeting the requirements of the output circuit power supply interface. Instructions for Use

The input circuit defaults to a single circuit

D dual circuit (mutually isolated)

Input signal (dual input identical) 1 4-20mA

2 1-5V

3 0-10mA

4 0-5V

5 0-10V

*Output 1 4-20mA

2 1-5V

3 0-10mA

4 0-5V

5 0-10V

The second output 0 defaults to no second output

1 4-20mA

2 1-5V

3 0-10mA

4 0-5V

5 0-10V

The default power supply mode is AC 220V

D DC 24V

Principle of action

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Reason for interference

(1) Ground circulation interference

To achieve monitoring and control in industrial production processes, various automation instruments, control systems, and actuators are required. The signal transmission between them includes small signals ranging from weak to millivolts and milliamps; There are also large signals of tens of volts, thousands of volts, and hundreds of amperes; There are both low-frequency DC signals and high-frequency pulse signals, which often cause mutual interference between instruments and equipment after forming a system, resulting in system instability and even misoperation. In addition to the performance reasons of each instrument and equipment itself, such as anti electromagnetic interference, another very important reason is that various instruments and equipment need to be grounded according to requirements and purposes. For example, for safety, the chassis needs to be grounded; In order for the circuit to function properly, the system needs a common reference point; In order to suppress interference and add a shielding cover, the shielding cover also needs to be grounded. However, due to the potential difference between the reference points of instruments and equipment (i.e. different common points of each device), the problem of "ground circulation" and "ground circulation" must be solved in the signal processing of the system.

(2) Natural interference

Lightning is a major natural source of interference, and the interference generated by lightning can be transmitted thousands of kilometers away. The time-domain waveform of lightning interference is a large spike pulse superimposed on a random pulse background. Cosmic noise is generated by ionizing radiation and constantly changes throughout the day. The solar noise changes dramatically with the activity of the sun. Natural noise mainly interferes with communication, while lightning energy sharp bee pulses can cause damage to many devices, which should be avoided or reduced to minimize losses.

(3) Human interference

The fundamental cause of electromagnetic interference is the variation of voltage or current in conductors, that is, larger dv/dt or di/dt. dv/dt or di/dt can cause electromagnetic wave radiation in conductors. On the one hand, people can use this feature to achieve specific functions, such as infinite communication, radar, or other functions; On the other hand, electronic devices generate accompanying electromagnetic radiation due to dv/dt or di/dt in conductors during operation, which objectively pollutes the electromagnetic environment for any subjective purpose. In addition, factories and enterprises often have large equipment (motors, frequency converters) frequently turned on and off during the production process, which can cause capacitive and inductive interference and affect the normal display or acquisition of instruments and meters. In any situation where there is a sudden change in voltage and current, there will definitely be electromagnetic interference present. Digital pulse circuits are a typical interference source, and with the widespread application of electronic technology, electromagnetic pollution will become increasingly severe

Resolve interference

The first three elements of interference are interference source, sensitive source, and coupling path. Without one of these three elements, electromagnetic compatibility issues will not exist. Therefore, we need to start from these three elements. Finding a convenient solution is usually not possible for interference sources and sensitive sources. It is common to find a solution through coupling paths. Such as using shielding, filtering, and other methods. Dealing with ground circulation is common and troublesome, and this is the topic for discussion below.

(1) * Method: All on-site equipment is not grounded, so that all process loops have only one grounding point and cannot form a loop. This method seems simple. However, it is often difficult to achieve in practical applications because some devices require grounding to ensure measurement accuracy or personal safety, and some devices may form new grounding points due to long-term corrosion and wear or climate effects.

(2) The second method is to make the potential of the two grounding points the same (as shown in Figure 1, V1=V2), but due to the influence of geological conditions and climate change on the grounding resistance, this method cannot be completely achieved in practice.

(3) The third method: Use signal isolators in each process link to disconnect the process loop without affecting the normal transmission of process signals, thus completely solving the problem of ground loop

superiority

The use of signal isolation methods in various process loops can be achieved through the use of isolation cards such as DCS or PLC, or on-site transmitters with isolation (some equipment can achieve this), or through the use of signal isolators. Compared to other methods, using signal isolators has the following advantages:

·In the vast majority of cases, using signal isolators and non isolation cards is cheaper than using isolation cards

·Signal isolators have superior performance in isolation capability and electromagnetic interference resistance compared to isolation cards

·The signal isolator is flexible in application, and it also has functions such as signal conversion, signal distribution, and interface conversion, making it more convenient to use

·Signal isolators usually have single channel, dual channel, and completely independent channels, which make the system configuration and daily maintenance more convenient

How to choose

How to choose isolators with varying prices?

The isolator is located between two system channels, so when choosing an isolator, the first step is to determine the input and output functions. At the same time, the input and output modes of the isolator (voltage type, current type, loop power supply type, etc.) should be adapted to the interface modes of the front and rear channels. In addition, there are many important parameters related to product performance, such as accuracy, power consumption, noise, insulation strength, and bus communication. For example, noise is related to accuracy, power consumption and energy are related to reliability, which require users to carefully choose. In short, applicability, reliability, and cost-effectiveness are the main principles for choosing isolators.

Standard series guide rail structure, easy to install, can effectively isolate; The potential between the input, output, solenoid valve, and ground can overcome various high and low frequency pulsation interference of the frequency converter noise level.