Safeguard

Protection range and parameters

Protected range

Input impact protection includes: short circuit, open circuit, wrong connection, etc.

shock and interference during operation,

the environment has high and low temperature difference and humidity difference.

The accuracy of long running or shelving.

Output impact protection includes:

Power consumption and thermal limitations at failure,

power consumption and thermal limits under working conditions,

high heat limit caused by short circuit distribution and automatic load output open circuit,

Limitations on the output of trusted objects and interference from the surrounding environment.

The safe value limit of the output energy.

Protection parameter

1. Power-on shock protection

Power-on surge current > 2 times normal operating current, the slow-start circuit causes the power-on voltage to rise slowly from 0V (>20mS) to the rated value, which is ramped to eliminate the inrush current. External protection power supply, internal protection of instrument components.

2.Power reverse connection protection

The power supply is reversed, the inverting diode clamps the meter power supply to -1V, and the reverse current is limited by the self-recovery fuse to 0.3~0.5A. When reversed, the self-recovery fuse will generate heat, but will not be disconnected; the reverse connection will be removed, and the self-recovery fuse will return to normal temperature and return to normal operation.

3.Distribution protection

Power distribution short circuit or current > 28mA (± 2mA), it enters the protection state.

When protecting, the protection tube works in the switching state; the voltage drop is zero when conducting, and the current is zero when disconnected. Thereby the carrying power is zero. It does not generate heat and is suitable for micro-packaged devices. After the fault is removed, the protection tube automatically resumes the conduction state without restarting (the protection tube has a voltage drop of zero and does not carry power). The magnitude of the protection current can be accurately located. Note: The distribution output clamp current can be customized according to the needs, please specify when ordering. The factory default is 28mA (±2mA).

4.Output protection

The output clamp current is 25mA (±1mA) to protect the successor device.

When the output load is 0Ω, the load supply voltage drops <1V and the power supply is <20mW. The load drive tube voltage drop is maintained between 0.3 and 0.7V, even when the load is equal to 800Ω, and no heat is generated in the output circuit.

5.Port protection

When there is a surge voltage or incorrect wiring:

The power supply, input, and output between the two terminals of the self-loop can withstand the external circuit voltage of <±24V rms, without damage.

Input, output, and power supply can withstand 2500V RMS / 1 minute without damage. Between the input, output and ground, it can withstand 2500V RMS / 1 minute without damage.

The short circuit formed by the misconnection of the terminal is open circuit and is not damaged.

The error between the meter head and the base is inserted.

6.Power protection

The self-recovery fuse of the power input circuit protects the power supply when the meter is shorted, with a limit of 300mA.

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Power requirement

1.power supply requirements

Dual redundant power supplies ensure uninterrupted power.

The power supply has fault self-diagnosis capability, and the power supply output voltage exceeds the high limit and is less than the low limit automatic open circuit to ensure that the redundant power supply enters correctly when the fault occurs.

>20mS slow start process, limiting the startup process Inductive load generates high voltage on the power line, and capacitive load generates overcurrent.

The power output needs to be connected with a lightning protection grid, so that the power supply load can be equipped with a power lightning protection function.

2.Power wiring

The power supply must use the power supply with the input and output isolated from each other. The negative pole of the power supply and the negative pole of the busbar backplane should be connected separately to ensure that no other branches are connected to the negative pole of the backplane. Otherwise, the reference point potential will be raised and the supply voltage of the backplane will be lowered. After that, the single line of the negative electrode of the backplane is connected to the ground, so that the zero current and the zero potential difference are maintained between the negative pole of the backboard and the ground, and the power supply current does not flow to the ground. This ensures the smoothness of the system reference point and device safety.

(If you do not use the bus method to supply power, especially when configuring more safety barriers (isolators) in a single instrument panel, the power line grouping method should be used to supply the safety barrier (isolator). The load of each group of lines should not exceed 15 and it should be soldered to the power terminal after multi-core wire soldering. This method is commonly used to effectively reduce the temperature rise on the power terminals, but it also increases the wiring and confusion in the disk. For example, there are 100 meters  and it is necessary to add more than 10 power lines and ground lines. In particular, the system ground reference point has become chaotic and uncontrollable.)

3.Increase the power supply voltage and reduce the power supply current

The power supply range is 15V-42V, and the maximum power supply is 50V. Power circuit efficiency >90%, no heat.

The power supply circuit is in the form of a switching regulator. The higher the power supply voltage, the smaller the supply current. Under the premise of conditional conditions, the recommended value of the supply voltage is 35V (compared to 24V power supply, the supply current can be reduced by 30%), which can effectively reduce the loss on the power line and the temperature inside the disk.