Mission Critical applications such as communication equipment rooms (such as 4G, 5G base stations) and data centers (IDC) will have a great impact due to power failure. Therefore, such constructions will have emergency power supplies such as UPS. In order to save energy, these data centers also desire to directly use regenerative energy or the DC voltage of the UPS to reduce the consumption of the conversion.

Therefore, in addition to AC input, the current power supply also supports 48V DC input LVDC and 180~400V DC input HVDC. When testing this type of power supply, the conventional AC power supply does not have the DC mode, so it is difficult to perform the test.

GW Instek ASR-2000 series and ASR-3000 series AC/DC power supplies are instruments developed for the above applications.

Precautions for purchasing AC and DC power supply:

1. Whether the DC power is the same as the AC power (commonly known as the DC full power): The DC output power of most products is only 80% of the AC output power, and there are even 50% of the AC output power. GW Instek ASR-2000 and ASR-3000 are designed for full power without reduction.
   
   

2. Whether it can be seamlessly converted from AC output to DC output: Most AC/ DC power supplies turn off AC and then turn on DC, so there will be a power outage at the moment of conversion. GW Instek ASR-2000 and ASR-3000 are seamless transition designs.

Connecting the power supply to the device under test (DUT or DUC) requires an additional test lead, and the resistance of the test lead will cause a slight voltage drop, so that the DUT cannot get the expected output voltage. In order to improve this problem, the power supply is designed with the function of Remote Sense. The remote sense function senses the actual voltage value received by the DUT through the additional wiring of S+ and S-.

Take the 3.3V output as an example, because the voltage drop of the wire, there is only 3.2V left on the circuit under test. Through the report of the remote sense, the power supply will increase the output until the voltage reported by the remote sense is 3.3V, this design can eliminate the voltage drop of the wire.

Precautions on using Remote Sense:

1. Remote Sense cannot be disconnected. Once the remote sense is disconnected, if it reports that there is no voltage at the DUT, the power supply will continuously increase the output to compensate. The remote sense still reports no voltage due to disconnection, and the power supply will increase the voltage again, which may lead to circuit overvoltage and burn. In order to avoid this problem, the remote sense design of many power supplies of GW Instek has the design of compensation upper limit.
   
   
2. If the output of the power supply uses an external switch to connect to the DUT, take a precaution on the wiring of the remote sense.

Test fuses and circuit breakers need transient current to test whether the operation is normal.

It is a design issue when it does not disconnect as the function  

It is a quality issue when it does not connect as the function

GW Instek electronic loads with the Turbo mode can help users to verify these two issues at the most appropriate cost.

Turbo mode can provide double the rated current or power in a short time (1 second).

Electronic loads with the Turbo mode include:

AEL-5000系列GW Instek brand: The AEL-5000 series

3310G系列，3350G系列，3270系列，3282系列Prodigit brand: the 3310G series, the 3350G series, the 3270 series, the 3282 series

Other applications of Turbo mode: Short circuit of AC power supply, OCP, OPP test

The basic element of an electronic load is a MOSFET, which is a voltage-controlled variable resistor.

The electronic load is an important device for testing the transient response of the power supply. If we simplify the electronic load as a MOSFET, when the MOSFET is connected to the power supply, the voltage of the power supply must reach the MOSFET Vds voltage before current flows through it. . Therefore, the electronic load cannot be started at zero voltage from its basic structure.

How do you accomplish a zero voltage startup application?

You only need to connect a power supply in series to offset the voltage change of Vds to start at zero voltage.

Possible applications: supercapacitors, fuel cells

PEL-3211 booster can only be connected in parallel with PEL-3111.

Five PEL-3111 units can be connected in parallel or PEL-3111 can be combined with PEL-3211*4

A maximum of five electronic loads of the same type as PEL-3021 or PEL-3041 can be connected in parallel.

Five PEL-3021 units can be connected in parallel

Five PEL-3041 units can be connected in parallel

The same is true for H series high pressure models

Application keyword: parallel connection of electronic loads

The DC mode of the AC power supply does not have the constant current (CC) output of the DC power supply.

The DC mode of the AC power supply can only provide a constant voltage (CV) output. When the DC power supply is overloaded, it will become a constant current (CC) output. When the DC mode of the AC power supply is overloaded, the output will stop.

During the production line test, the programmable DC power supply provides voltage, current, and test time. These three programmable variables enable the automation of complex production line test procedures. However, if you want to further improve the test capacity after automation, you must understand the design and special features of programmable power supply.

First, we need to understand the output characteristics and load effects of the DC power supply.

In order to provide a stable DC output, the DC power supply will have a capacitor at the output to perform the filtering work, and the capacitor does not allow the voltage to change instantaneously, so when you want to change the voltage output, the DC output filter capacitor will make this change a dilemma of application. The smaller the output ripple, the slower the response speed of the voltage change.

The output voltage should become larger: fast when no load, slow when loaded. Life scenario: A car full of passengers and an empty car climb a hill. Under the same throttle condition, the empty car climbs quickly, and the fully loaded car climbs slowly.

The output voltage should be smaller: slow when no load, fast when loaded. Life scenario: a car full of passengers and an empty car go downhill. When the accelerator is not stepped on, the empty car goes downhill slowly, and the full load goes downhill fast. When the power supply provides the function of the bleeder resistor, the voltage reduction time can be increased through the bleeder resistor.

If you need the power supply to perform rapid voltage changes (100u sec level), you can use the DC mode of the AC power supply, such as GW Instek ASR-2000 series, ASR-3000 series AC/DC dual-purpose power supplies.

If a rapid change in current is required, an electronic load can be used to extract the load, forcing the power supply to provide fast current.

In addition to the above issues, the setting time of the hardware and the computer control interface (GPIB, RS-232, USB, LAN) adopted will affect the time of the programmable voltage change.

Application Keywords: Rise Time, Fall Time

The output of most DC power supplies is to provide a set voltage, which we call the constant voltage mode (CV mode). It is better to use "set fixed output voltage" to describe the overall meaning. At this time, the current of the power supply varies with load change.

However, this fluctuating current cannot exceed the maximum design current of the power supply (to meet the application and price design goals) or the maximum set current (to protect the circuit under test), so once the load current exceeds any of the above current values, the output of the power supply will switch from CV mode to constant current mode (CC mode)

Take the DC power with the maximum design voltage/current of 30V/3A as an example: when the load does not exceed 3A, the power supply is in constant voltage mode, and the set output voltage can be 0~30V (according to the minimum set resolution). Taking 12V as an example, as long as the load does not exceed 3A, the ideal output voltage is a fixed 12V (the unideal value is affected by the output accuracy, ripple/noise, linear regulation, load regulation), and the current value varies with load change.

Once the load exceeds 3A (according to Ohm's law 12V/3A=4 ohms, when it is lower than 4 ohms, the load will exceed 3A), since the power supply can only provide 3A, it will be converted to constant current mode at this time, the current is 3A, the output voltage varies with load change.

The relationship between load, current and resistance is as follows: Generally, the reason why the current does not reach the set current is that the resistance is not small enough.

Large load = large current = small resistance; small load = small current = large resistance

How to set the maximum current:

Knob-type setting: The output must be short-circuited to see the current reading. It is recommended to turn the knob to the state where the current is 0. If the knob is at the maximum current position, there may be sparks when the output is short-circuited (possibly frightened). Slowly turn the knob from the position where the current reading value is 0 to the desired maximum setting current.

Key-press setting: Just use the numerical and unit keys to input the required maximum setting current.

Application keywords: constant current output, constant current output

Step 1: Check whether the AC input of the power supply is normal? Is it because the power strip controlled by the switch is forgot to turn on or was turned off by a colleague without being noticed. Check whether the display on the power supply has a display, if not, please check whether the fuse of the power supply is blown.

Step 2: After confirming that the power input is normal, set the output voltage and current of the power supply, both of which cannot be 0 (especially note that the current cannot be 0). If it is found that the setting value cannot be displayed, some GW Instek models provide a keyboard lock function to ensure that the setting value is not misused during the test. Please confirm whether the model you are using has this function. If so, please confirm that the Key Lock indicator is off, if the Key Lock light is on, please unlock it first. If the power supply still cannot be set, please confirm whether the power supply is connected to the computer. If the computer is connected, the remote control mode will cancel the Local operation.

Step 3: If the power supply has an output control switch, please press on. Power supply with an output control switch often has a light signal indicating that the output is turned on.

Step 4: If the output control switch is turned on and the light is not on (the light may be faulty, but the power supply still has output), please use the voltage range of a multimeter to measure the output of the power supply. There are several power supplies of GW Instek with on/off delay timer function. Please also check whether the output has a time delay because this function is turned on.


If the power supply still has no output after the above steps, please contact your nearest GW Instek Service Center to arrange for the instrument to be repaired. 

Service Support:
services@goodwill.com.tw

The launch of GSM-20H10 is to provide users with a more economical choice on the entry-level Source Meter.

Therefore, we also take into account users’ requirements to replace the instrument. Therefore, all the commands on Keithley 2400 can be recognized and executes by GSM-20H10.

But there are two special cases users must consider:

1. GSM-20H10 is much faster than Keithley 2400 in terms of the speed of CPU processing. When the test system is very sensitive or strict to command sequence, time adjustment on commands may be necessary.
2. Keithley uses some unpublished commands in the software, which limit the direct replacement of GSM20H10.

When the output Current level exceeds 3A, the overload indicator turns red and CH3 operation mode switches from Constant Voltage to Constant Current. Note:"overload"in this case does not mean an abnormal operation please remove your load then overload indicator would be turns off if you have higher voltage and current requirement you can shift to CH1 or CH2 for operating.

The LOCK key to lock the front panel key operation. When the LOCK key function enable that the LED turns on. To unlock, press the LOCK key for 2~3 seconds then the key LED will be turn off.