HZ-3110B has 7 current modes: AUTO,<20mA, 40mA, 200mA, 1A, 5A, 10A. Many people choose AUTO for convenience, but understanding the applicable scenarios for each gear can make testing faster and more accurate.

The correspondence between current gear and range

Each current level corresponds to a measurement range. When the range is exceeded, the instrument cannot establish a stable current and will continue to display the "charging" status

10A gear: suitable for 0.5m Ω~0.8 Ω (low voltage winding of large capacity transformers, large section busbars)

5A gear: suitable for 2m Ω~4 Ω

1A gear: suitable for 10m Ω~20 Ω

200mA range: suitable for 100m Ω~100 Ω

40mA level: suitable for 1 Ω~500 Ω (high voltage winding of small and medium-sized transformers)

<20mA range: suitable for 100 Ω~100k Ω (high resistance values such as voltage transformer windings)

In terms of accuracy, the accuracy is ± (0.5%+2 words) in the<20mA range, and ± (0.2%+2 words) in all other ranges. The accuracy of high resistance measurement is slightly lower in the<20mA range, which is the inevitable cost of decreased signal-to-noise ratio when the current is low.

Why does the higher the current, the faster the measurement

The transformer winding is an inductive load, and during measurement, it is necessary to first "magnetize" the winding to stabilize the current to the set value. The magnetization time depends on the time constant (L/R) of the winding. The larger the inductance and the smaller the resistance of the winding, the longer the magnetization time.

Choosing a larger test current is equivalent to increasing the driving energy, which can significantly shorten the magnetization time, make the current reach a stable value faster, and obtain measurement results faster. For the low voltage winding of a large capacity transformer (with a resistance of only a few milliohms), measuring time using 10A mode may be several times shorter than using 1A mode.

What is the significance of the maximum output voltage 24V of HZ-3110B

For high resistance windings (such as the primary side of a voltage transformer), if the output voltage is too low, even with the minimum current setting, sufficient current cannot be established. The maximum output voltage of HZ-3110B is 24V, ensuring that it can still provide effective current when measuring high resistance values (close to 100k Ω), avoiding the instrument from being stuck in the "charging" state for a long time.

Where is AUTO gear suitable for

When the resistance value of the measured winding is uncertain, first use the AUTO mode, and the instrument will automatically select the appropriate current mode based on the detected load resistance value to avoid selecting the wrong mode and exceeding the range. After determining the resistance range, switching to the corresponding manual gear can obtain a more stable measurement state.