Requirements for the Installation and Operating Environment of Electronic Measuring Instruments

15 Jun 2019

The installation and operating environment of the electronic measuring instrument and its system are good, which directly affects the performance and service life of the instrument. For large test systems, such as circuit board test systems, engineers must survey the site and visitSMT Exhibition before installation, and at the same time hand over the site preparation to the end user to discuss the site selection and preparation plan with the user.

1. The choice of venue should avoid the following external factors:

Electromagnetic fields, flammable or flammable gases, magnetic fields, explosives, power noise, moisture, corrosive gases, dust, SMT Exhibition, etc.

2. There should still be enough space for the equipment and equipment to be used by the operation or maintenance personnel after installation. At the same time, there should be enough space for heat dissipation before and after the equipment.

3. The site should be kept clean and dust free.

4. The carpet should be banned on the site. The static insulation pad should be installed at the entrance of the equipment. The operator should also wear an anti-static wristband when using the instrument.

5. Direct sunlight should be avoided.

6. The instrument handling route has sufficient width and height to allow the instrument to be transported to the site of use.

7. Any Radio Noise Interference (RFI) should be lower than the standard specified in the SMT Exhibition instruction manual.

8. The load on the floor between the equipment is sufficient to support the weight of the instrument.

9. Facilitate the entry and exit of personnel and equipment.

10. There is a suitable emergency exit.

In order to maximize the performance of test instruments and systems, that is, to reduce instrument failure and ensure SMT Exhibition equipment performance indicators, good operating environment planning is essential.

Environmental considerations include the temperature and humidity of the site, the dust content of the air, the vibration of the site, and the noise interference of the electromagnetic field.

Temperature and humidity

As we all know, electronic devices emit heat during the work process, and the electronic devices at SMT Exhibition themselves have a certain range of operating temperatures.

The closer the operating temperature or ambient temperature is to the upper limit of the operating temperature of the instrument, the more the performance index of the electronic device becomes worse in geometric progression. In other words, an instrument that can operate for 10 years in a 25-degree environment may only work for 3 years in a 45-degree environment. The proper working temperature is a necessary condition for the instrument's "longevity".

The performance indicators of the instrument are measured under SMT Exhibition certain circumstances. Note that the conditions of use of each instrument are different. Some are suitable for field work, while others are suitable for laboratory use. Please read the operation instrument carefully. It is recommended to place desiccant in the storage box. Get wet.

The damp environment is especially "killing" for electronic measuring instruments. Under certain humid conditions, the impedance characteristics of the devices on the printed circuit board of the instrument may change abnormally, and even cause a short circuit.

Air dust content

The operating environment should be kept clean and dust-free. The impurities in the air greater than 0.5 Micron should not exceed 45,000 in the air per cubic meter. Excessive dust in the air can easily cause poor contact and disk read and write errors, and the magnetic head is bad.

Users who use the manufacturer's 871X series network analyzers on the production line, especially those who produce ceramic filters, often complain that the 871X floppy disk drive often cannot read data and is prone to failure.

If these users are fortunate enough to see the detached 871X floppy drive, thick dust, ceramic powder, and heavily contaminated floppy drive heads, no one would expect any brand of floppy drive to work in this harsh environment.

Site tremor

The site jitter should not be greater than 0.5G and should not be placed with the machine that generates the vibration, because SMT Exhibition the vibration will cause the mechanical parts, joints, panels and motherboard contact parts of the instrument to loosen and cause abnormal work.

Electromagnetic field noise interference

Use of radio noise near the SMT Exhibition venue should be below the standards specified in the instruction manual. If there is a strong magnetic field or a large microwave transmitter station near the site, the site should be relocated. Otherwise, please shield the surrounding area with metal to reduce the interference to the standard.

The user of the manufacturer's wireless integrated tester may have experienced this experience. After the tester repeatedly produced misdetected on the production line, it was confirmed as “no hardware failure” after being sent to the repair center, and the fault was still installed on the production line. After the on-the-spot investigation of SMT Exhibition the engineer, it was found that the local area of ​​the production line was contaminated by strong wireless noise. This is the source of the "false detection" of the instrument.

Requirements for power supplies

The installation of any instrument and system, power supply is an important consideration, the better the external power quality (refer to voltage, frequency changes, filtering effect), the better the use. If you have concerns about the quality of your power supply, you can use a power detector or oscilloscope to monitor changes in the power supply to understand its reliability.

Voltage, frequency, allowable change specification

Voltage: single phase 220V+5%~-10%

Frequency: 48Hz~66Hz

The instantaneous voltage can't exceed 220V+5%, -5%, and the well must be restored to 220V in 25 cycles (0.5 seconds). For computer systems, it must be restored in three cycles. The total harmonic SMT Exhibition component must not be high. At 5%.

Instantaneous impulse voltage

If the instantaneous impact voltage is greater than 100V, it will cause problems in the equipment.

Note: The above data is for reference only. Different devices have different power supply specifications SMT Exhibition. Please read the operation manual or the site preparation manual carefully to determine the power supply specifications.

Beating melody

Adding the power required by all equipment and adding at least 30% or more is a requirement for future expansion.

The grounding wire must be completely isolated and insulated from any conductor and can only be connected to the power neutral (neutral) at the true grounding of the building. The ground wire diameter is at least 3.5mm. The ground wire is not the power neutral (neutral) and must be separated from the neutral (conceptually). The grounding SMT Exhibition impedance shall not be greater than 2 ohms when measured between the neutral and ground wires of the power outlet (measured with a grounded impedance tester). The voltage between the neutral and ground wires measured at the power outlet shall not exceed 1.0V.

At the same time, the voltage change must not exceed 1.0V regardless of whether the device is turned on. The grounding wire cannot be replaced by an iron pipe, and the grounding resistance measured at the grounding end of the grounding wire is not more than 1 ohm.

The chassis of the manufacturer's instrument is mostly connected to the ground wire of the instrument itself, so the direct consequence of the poor grounding of the instrument is that the fuselage is charged, which is a potential danger to the operator and the instrument itself.

When using the instrument, the user may extend the power cord due to the requirements of the test environment, increase the power supply terminal block. In many cases SMT Exhibition, the floating ground is caused by the use of inferior or undesired wiring boards, if the neutral and neutral wires are in the middle link. Incomplete isolation, the fuselage may have 220VAC mains, which is fatal.

Of course, this is a more extreme example, as long as we operate in strict accordance with the grounding procedures, good grounding is guaranteed.

Power supply wire

The power supply wire provided by the manufacturer is matched in polarity with the power socket on the instrument device, and the power socket prepared by the customer must be in accordance with the power supply wire in polarity, otherwise a deadly voltage may exist. At the same time, the instrument will be seriously damaged, so please pay attention to the polarity of the power socket to ensure the safety of personnel and equipment.

Power outlet

Generally speaking, each instrument has at least one power supply station. Some instruments may have additional power sockets on the rear panel. This socket can be used by other peripheral devices, thus reducing the number of external power sockets.

L, N, G on the power socket and plug respectively indicate:
L: FireWire
N: center line (neutral line)
G: ground wire

Insurance

When the instrument is used with different voltages, the insurance specifications used will also change. Refer to the specifications listed in the instrument operating instructions for replacement. The fuse has a fast melt and a slow melt. Do not change the specifications.

Power selection switch

In order to adapt to the power supply system of different countries, the manufacturer's instrument is equipped with SMT Exhibition a voltage selection switch (220VAC or 110VAC). When the user first accepts or uses the instrument, be sure to confirm that the power switch on the instrument is set on the power system currently being applied. Otherwise Will cause abnormal operation of the instrument.

Of course, many instruments currently use adaptive power modules, and no longer have to worry about the setting of the power selection switch.

Rated current

If you want to determine the rated current required by the test system, first list the current required by the various instruments included in the system, and then multiply the sum of all the device currents by 2 to get the rated current required by the system.

This current value is sufficient to tolerate sudden current fluctuations and to the occasional addition of equipment SMT Exhibition, and the size of the wire passing through during power distribution construction is also calculated accordingly.

Power wiring engineering

When constructing the power wiring project, please pay attention to the following three points: 1. Use a dedicated switch box;

2. The capacity of the air switch should be greater than the sum of the capacity of all instruments and equipment on the branch;

3. The air conditioning system must not be connected to the same power source as the test system;

Safety precautions before system installation on site

First, from the safety considerations of both personnel and equipment, be sure to inform the site preparer to provide correct, regulated power conditions before performing a site installation.

Secondly, before installing the system, the engineer must check the external power supply 220VAC and confirm as follows: Is the total power supply really grounded SMT Exhibition properly; whether the resistance between the neutral line and the ground line is less than 2 ohms; whether all 220AC ground terminals are correct Ground; the terminal block meets the left zero right fire.

If no ground wire is provided and floating occurs, connect a wire to the ground at the ground end of the instrument's rear panel instead of using the two terminals.

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