FAQs Library
How to measure the quality of GD20UL main circuit?

Switching the multimeter to Diode position and test as follows:

1. Set the multimeter to Diode position, connect the black hand with "+", then connect the red hand with R、S、T、U、V、W in order, if all the values is between 0.3--0.5V, both the rectifier and IGBT upper bridge are good. 

2. Contrary, connect the red hand with "--", then connect the black hand with R、S、T、U、V、W in order, if all the values is between 0.3--0.5V, both the rectifier and IGBT lower bridge are good.

If the test values is highly unbalance, the rectifier or the IGBT must be broken. And you can't power on in this situation.

More details, please see the attached file.

Notice: Please make sure that the inverter no power, so we call it static test.


What's the reason that fuse and soft start resistance damaged for GD350 inverter?

There is a fuse on the 24 V auxiliary power board, this board will provide power for fan and soft-start contactor. If the fuse damaged, the 24V auxiliary power board will not output 24V power supply, in this case, contactor isn't close, the drive still trying to start with the resistor in the circuit, there  will have a big current through resistor. But in most cases, it will not burn up, because our VFD has protection for that. I will explain more: when the power goes into VFD through soft-start resistor replace of contator, the resistor will act as an Partial voltage resistance in the whole voltage range, for example, from DC 540V goes down to 350V, our VFD will report "UV" under-voltage fault, to protect the soft-start circuit. In very few cases, the VFD don't have time to protect while during voltage from DC 540V goes down to 350V.

Sometimes, the resistance shell is cracked due to heating, its inside resistor may not be broken, I supposed that. You can use a multi-meter to test the resistor value is 20Ω or not.

When VFD startup, after a few secdons, dEU failure is reported. How to solve it?

dEU is the speed deviation fault. Set the speed and detect the speed deviation. After the detection time is exceeded, the inverter will stop reporting the dEU fault. The reason may be that the load is too heavy or the rotor is blocked, which causes the speed deviation to be too large. It is necessary to check the load condition, extend the speed deviation detection time, and adjust the speed loop PI parameters according to the control mode to increase the reduced output torque.

How to solve the problem that no display when the GD20UL is powered on?

If the power indicator is on, the keypad does not display,  the possible causes of the failure:
1. The power supply of the driving power board is damaged or there is a short circuit;
2. The keypad wire is not in good contact or the keypad is burnt out;
3. The main control board is damaged;

If the power indicator is not on, the possible causes of the failure are as follows:
1. No input power;
2. The fuse is broken;
3. The rectifier bridge is broken.

GD350 applied in V/F operation is not stable, the output current is higher than the normal value, how to solve it?

Adjust V/f control parameters properly.
1. Slip compensation P04.09
2. Suppression of oscillation P04.10, P04.11, P04.12, P11.27 (VF oscillation suppression method selection, ones bit effective)
3. PWM selects the ones bit in P08.40

How to solve the problem that the GD20U's terminals invlaid?

Possible causes of failure:
1. The short-circuit connection jumper between terminal 24 V and PW is lost;
2. The voltage of terminal 24 V is abnormal;
3. The terminal is damaged;
4. The terminal polarity is set incorrectly;
5. Some parameter setting is improper, please reset to factory parameters, then test.

How to control the inverter via mobile phone Bluetooth?

GD350 needs to be equipped with a Bluetooth card, scan the QR code on the inverter, download and install INVT Workshop, and open the mobile phone Bluetooth to connect to the inverter. See the video link below for more steps.

What type of air compressor is GD300-01A suitable for?

GD300-01A is a dedicated inverter mainly developed for screw air compressors. For other types of air compressors, it is recommended that you consult our technicians to determine the specific control plan.

How about GD300-16 reduce pump logic details?

There are 3 parameters P22.24~P22.26 are used for setting the conditions of reduce motor:
1. P22.24 pressure allowance 100% is corresponding with P09.02.
2. If variable frequency motor runs frequency reach P22.20, and (PID feedback [P17.24] - PID given[17.23]) > Pressure allowance [P22.24]), this status keep time reach P22.26, meet condition of reduce motor.
3. P22.25 a limit frequency to reduce motor. When the system still have power freq. motor, and VFD output reach this P22.25, keep time reach P22.26, start to reduce the power freq. motor.
4. Also when added a power freq. motor, VFD also output this setting frequency P22.25, then adjust by PID, avoid pipe pressure fluctuation.
5. When reduce motor, VFD operate the relay to switch-off power freq. motor, at the same time, increase output frequency to P22.20 with P22.28 ACC time(if P22.27=1), then adjust output frequency by PID. In order to avoid pipe pressure fluctuation.

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