Electrical energy saving

Voltage isolation energy saving characteristics

Transformer feedback voltage isolation circuit electrical characteristics

Low drift. . . . . . . . . . . . Typical value of 20nV/°C.

Low imbalance. . . . . . . . . . . .Typical value 20μV.

High precision. . . . . . . . . . . . 0.01% FS maximum.

Micro power consumption. . . . . . . . . . . . 0.4mW / each way. 

Transformer feedback voltage isolation circuit characteristics

Parallel mode is used to realize multi-channel expansion of isolated signals; on the basis of one transformer, adding one winding can increase one isolated output voltage and only increase power consumption by 0.4mW. It is used for one-in and two-out products. Compared with the current transformer isolation mode, the layout area is reduced by 30%, and the power supply power saving ratio is higher than 40%.

The input signal is extended to zero or negative.

The application method is simple and flexible. The signal voltage does not need to be converted and directly enters the isolation circuit. The signal current is sampled through the resistor into the isolation circuit. The isolated output does not require I/V/I repeat conversion, and V/I is completed at one time.

The transformer feedback voltage isolation characteristic can be used to easily realize single-machine stencilization and the modular circuit structure is short, small, light and thin. 

Transformer feedback voltage isolation schematic


Load adaptive energy saving

Load adaptive circuit electrical characteristics

Load monitoring, adaptive output, no heat generation, the output circuit saves 70% on average.

The output circuit is powered by an independent switching power supply. The supply voltage is automatically adjusted according to the size of the load. The output adjustment tube uses a micro-package device, and the voltage drop is always <0.8V, and no heat is generated.

When the load is short-circuited, the power supply is automatically adjusted to <0.8V, and the regulation tube power consumption <(20mA*0.3V=)6mW, no heat.

When the load changes from 0 to 800 Ω, the output current changes by less than ±2 μA.

The load selection is uniform to 0−800Ω, no need to specify the load size. When using a small load, the output voltage of the output circuit automatically drops, and the 24V supply current decreases.

The average control system load is only 120Ω (Note). Compared with the non-regulated products with a maximum load of 800Ω, the power-saving ratio of the load adaptive output circuit is (1-120Ω/800Ω =) 85%, which is higher than 70% after the power efficiency is deducted.

(Note: According to 100 units, 90 units are 50Ω and 10 units are 750Ω average. The output power of non-regulated products is fixed at the power required by the maximum load. When the external load is less than the maximum load, the excess power is withstood by the internal high-power tube. The total output power is unchanged)

Practical description of load adaptation

When the external load is the maximum load that the meter can drive, the output circuit itself consumes the least power, that is, the static power consumption, and does not generate heat, because the heat is output to the external load. But in turn, when the external load is small or even short-circuited, the output circuit must withstand the maximum load power, and then add its own static power. At this time, the external load is small, does not bear power, and heat is concentrated on the output circuit.

The maximum load capacity is determined by the highest voltage assigned to the output circuit. It is also artificially set. For example, the minimum voltage of 800Ω requires 20mAx800Ω=16V. The minimum voltage of a common 50Ω load only needs 20mAx50Ω=1V, and the load power is 0.32. W, 0.02W. If the voltage is not automatically turned down, the 16V power supply required by 800Ω is still charged at 50Ω load, the wasted power consumption is 0.32-0.02=0.3W, the power consumption is only 6.25% of the power consumption, and the remaining part is converted into heat and left in the meter.

Load adaptive circuit electrical schematic


Bus power supply energy saving characteristics


Parallel busbar backplane power supply mode  

The 5-wire double-sided parallel method forms the grounding wire and the positive pole of the power supply line, and forms an integrated busbar on the guide rail without a connection point. The cumulative copper width of a single busbar is >3mm *4=12mm. The line resistance is 0.041 Ω/m. (The thickness of copper foil is 0.035 mm, the cross-sectional area is 12*0.035=0.42 mm², the electrical conductivity is 0.0172, the length is 1 m, and the linear resistance is R = 0.0172*1/0.42=0.041 Ω/m).

Example under extreme application conditions:

1.2m long busbar backplane guide, double line resistance is measured in 0.1Ω.

The average current of 100 meters on the busbar is 50mA ╳ 100=5A, and the voltage drop of the busbar (0.1Ω*5A=) is 0.5V.

The base is connected in parallel with the busbar. The single contact resistance is 0.3Ω, the single-sheet operating current is 50mA, and the voltage drop of the busbar and the base (0.3Ω*50mA=) is 15mV, which can be ignored. If the contact resistance is increased by 20 times due to poor contact, the voltage drop between the busbar and the base is 6Ω*50mA = 0.3V, which can be ignored.

Auxiliary power terminal

When used in bulk, it should be connected to the power supply through the backplane bus. Under normal circumstances, the auxiliary power terminal is only used when testing or only a small number of meters.

It is not recommended to use two-wire series connection on the auxiliary power terminal, or use the series splicing type bridge and bridge power supply method; set the contact resistance of each table connection point to 5* 2=10mΩ, the resistance value of 100 table connection points is 1Ω, pass 5A current pressure reduced to 5V, power 25W; average power consumption per point of the table is 0.25W. Due to the large current at the connection point of the front section of the guide rail, the current at the connection point of the rear section is small, the heat is concentrated in the front section, and the heat dissipation is uneven, so that local high heat or even an open circuit is generated. When power must be supplied in the above manner, the power cables should be grouped, and the load of each pair of power cables should not exceed 15.

Bus power supply and power terminal series power supply comparison

After cutting the power cord and connecting them in series to connect the power terminals, the contact resistance will be generated. The number of contact resistors is twice the number of the meter. The contact resistance of each meter is 5mΩ. The total contact resistance of 100 meters is 1Ω. The current is 50mA, the total current of 100 meters is 5A, the voltage drop of the power terminal is 5AX1Ω=5V, and the power consumption is 5AX5V=25W. Each meter consumes 0.25W of average power on the power terminals, which is too large for most single-channel meters with a total power consumption of 0.5~0.7W.

Do not cut the power cable, directly crimp it into the power terminal, the power cable becomes a bus. Except for the resistance of the wire itself, there is no contact resistance between the power cable and the power cable, and each watch will be reduced by 0.25W. Power consumption. 

For example, the busbar adopts 1mm diameter pure copper wire, 2m length, the line resistance is (0.0172* 2 /(3.14*0.52) =) 0.043Ω, the voltage drop of 5A current on the 2m busbar is less than 0.25V, and the power consumption is 1.25W, which can be ignored.

There is still contact resistance between the busbar and the power supply terminal, but each contact resistance only passes through one meter current, an average of 50mA, the voltage drop is 50mA*5mΩ=0.25mV, and the power is 0.00025*50mA=0.0125mW. Can not count.

This method is effective, but the actual wiring is still relatively complicated; when the two thick wires are not cut and merged into one strand, the hardness is large, the terminals are not tightly pressed, and the watch is easily lifted by the wire; the wire is peeled off when the wire is not cut. It is not easy. Especially when the meter is made thinner, such as 6mm, the rationality of this method will be questioned.

Schematic diagram of busbar backplane used for cartridge table and card table  

Parallel busbar backplane power supply structure diagram