Solving the disturbances from system with signal isolator (isolation transmitter)

                        Solving the disturbances from system with signal isolation transmitter
       Solving the interferences from System with Jie ShengDa Technology signal isolator Now,let's look at the Cause interference wich from industrial automation and control systems.This helps to make full use of signal isolation to solve these problems.
       Jie Sheng Da Technology signal isolation Official Website: http://www.jsd-iae.com 
 signal isolation detailed technical data: http://www.jsd-iae.com/Isolation-Transmitter.htm

1: The cause of the interference from System
(1) ground loop interference
    In the industrial production process to achieve monitoring and control need to use a variety of automated instrumentation, control systems and actuators, signal transmission among them are small signal such as mV class,mA class. some are large signal such as tens of volts, even several kilovolts, hundreds of amperes ; existing low frequency DC signal, there are high-frequency pulse signal, etc., afeter constitute a system often exist mutual interference between instruments and equipment causing system instability or even misuse. This occurs due to each instrument and the performance of the device itself  such as anti-electromagnetic interference, anather very important reason is the variety of instrumentation equipment according to requirements and objectives are nedded to connecte to ground.for example for security, housing needs connected to the ground; the system have a common reference point for the circuit to work properly, for suppressing interference add shield, the shield can be grounded, However, due to exsit electric potential difference from the reference point of instruments and equipment.(that is to say the common ground is different from each device) and thus form a "ground loop" "ground loops" problem is must be solved in the system signal processing.
       As Figure 1, A is the measured signal grounding point, B is the test system grounding point,so formation ground A through the signal to the test system, And then pass through B, and into the ground back into A, to form ground loop.the testing signal of ground loop forms interfere, The A, B two points appear high common-mode noise voltage when the circulation voltage is large, and through the distribution parameters coupled to the signal line, or directly connected to the level signa line ,wich will cause a great series mode interference, even damage to the interface circuit and Instrumentation equipment So it can not be taken lightly, we must guard against!
(2): natural interference
       Lightning and electricity are a major source of natural interference, the interference caused by lightning and electricity can be transmitted to thousands of kilometers away.the wave shape being lightning interference is a big spike of random pulse superimposed random pulse.
       Cosmic noise is generated by ionizing radiation, constantly changing during the day. Solar noise along with the  solar activity changes dramaticly.
       Natural noise interference is mainly have a bad affect on communication.The lightning energy spikes can damage a lot of equipment, which should be avoided or reduced the extent of damage and reduce losses.

(3): human interference
    The root causes of electromagnetic interference is the change of  voltage or current in conductors, that is to say :larger dv/dt or di/dt.dv/dt or di/dt can make the conductor produces electromagnetic radiation. On the one hand, one can use this feature to implement specific functions, such as: wireless communications, radar, and other functions, on the other hand, when the electronic equipment works,the conductor will generate dv/dt or di/dt and accompany electromagnetic radiation.No matter for what purpose subjectively,caused pollution to the electromagnetic environment objectively  . There
factories and enterprises in the production process will often have some large equipment (such as motor, inverter, etc.) frequent switching, its will cause some capacitive, inductive interference, will also affect the instrument display or acquisition  normally. Where there are voltage or current mutations,certainly exsist electromagnetic interference. Digital clock circuit is a typical source of interference. With the extensive application of electronic technology, electromagnetic pollution will become increasingly serious.

2: The way to solve all sorts of interference
       The three elements are interference is the source of interference, sensitive sources and coupling paths, The electromagnetic compatibility problem will not exist if missing one of these three elements.Therefore, we need to find problem from these three elements.
       Find out the most convenient solution, generally the interference source and sensitive source are impossible, usually from a coupling path to find ways, is the most commonly method. Such as adding shielding or filtering and other means.Treatment "ground loop" is the most common and most troublesome, and now let's explore this topic.
(1) The first way: all field devices is not grounded,make all processing ground loop only have one point to connecte to the ground and can not form a loop, this method seems simple. But the practical application is often difficult to achieve, because some of the equipment requires to be grounded to ensure testing accuracy or personal safety, some devices may have formated new grounded pint because of the long-term corrosion and wear, Corrosion, wear and tear or climate impact.
(2) The second way: the two grounded points to the same potential (shown in Figure 1, let V1=V2), However, due to the resistance of the ground effects by the geological conditions,climate change, and many other factors, This method is in practice not fully be achieved.
(3) The third way: using signal isolator in all aspects of the process. disconnection process loop, without affecting the processing signal transmisst normally, thus completely solve ground loop problems (Figure 2)

3: The above various disturbances can be solved by adding signal isolator before the device. we take a look at using signal isolators have those advantages
   Using DCS, PLC or other isolation cards or isolation transmitter used in each process loop of the industrial site.(part of the equipment can be achieved), also can use signal isolators to achieve.signal isolation has the following advantages:
• vast majority of cases,using signal isolator+non-isolated cards cheaper than using isolated cards
• Signal isolator is superior to isolation cards in the aspects of isolation, anti-electromagnetic interference
• Signal isolators and flexible, it also has signal conversion ,signal distribution and interface conversion function, more convenient and flexible to use
• Signal isolators normally have one-input-one-output, one-input-two-output, one-input-three-output, one-input-four-output, two-input-two-output, three-input-three-output, four-input-four-output or more channels,the channel is completely mutual independent and constitute the system's configuration, routine maintenance easier.

Shenzhen Jie Sheng Technology Co., Ltd. (JSD Technology) one-input-one-output, one-input-two-output, one-input-three-output, one-input-four-output, two-input-two-output, three-input-three-output, four-input-four-output signal isolation transmitter technical data as follows: http://www.jsd-iae.com/Isolation-Transmitter.htm