The questions our engineers are asked most often about installing, wiring, parameterising and troubleshooting a SHZK 300N frequency drive — answered directly, without the generic filler common on most VFD sites. Click a question to expand the answer.
Frequently asked questions
What does an Err code on my SHZK 300N display mean?
Each Err number identifies a specific fault — for example Err14 is module overheating and Err09 is undervoltage. Find the exact code in our complete Err01–Err71 fault-code table, correct the cause, then press STOP/RST to reset.
Why does my VFD trip overcurrent as soon as it starts?
On a new installation the usual cause is running sensorless vector control without motor auto-tuning, so the drive uses generic motor values. Check for a short circuit first, then enter the motor nameplate data and run static or rotational tuning.
Why does the drive trip overvoltage when the motor stops?
A high-inertia or overhauling load generates energy back into the DC bus during a fast stop. Lengthen the deceleration time, or fit a correctly sized braking resistor across the P+/PB terminals if a fast stop is required.
Can I run a 3-phase motor from a single-phase supply?
Yes. A SHZK single-phase-input VFD accepts single-phase power on the R and T terminals and delivers a balanced 3-phase output on U/V/W. Size the drive for the higher single-phase input current, especially at 0.75–2.2 kW.
What happens if I connect the mains to U/V/W instead of R/S/T?
Applying mains voltage to the output terminals destroys the IGBT modules immediately and is not covered by warranty. Always confirm supply voltage is on R/S/T and absent from U/V/W before switching on.
Do I need to run motor auto-tuning?
If you use V/F scalar control it is optional, but for sensorless vector control — the default — tuning is essential for full torque and to prevent nuisance overcurrent trips. Use rotational tuning with the load decoupled, or static tuning when it cannot be removed.
How do I reset a fault after fixing it?
Press the STOP/RST key. Some overcurrent protections require a short wait (5–10 seconds) before they can be cleared. Always correct the underlying cause first or the fault will return.
What is the difference between Sink and Source input wiring?
In Sink (NPN) mode a digital input switches to COM; in Source (PNP) mode it switches to an external +24 V. Set the on-board jumper to match your switch or PLC output type — a mismatch is why a start command may appear completely dead.
How do I set speed with a potentiometer?
Connect the wiper to AI1 and the two ends to +10V and GND, then set the frequency source to AI1 (P0-03 = 2). Use shielded cable and keep it away from the motor cable to avoid speed hunting.
Can a 4–20 mA signal control speed?
Yes. Connect the current signal to AI2 with the return to GND, select current mode for AI2, and define the 4 mA and 20 mA points. This is the most noise-immune reference from a PLC or process sensor.
What size VFD do I need for my motor?
Match the drive to the motor rated current rather than only the kW label, and allow a margin for heavy-starting or constant-torque loads. Our engineers can confirm the exact model from your motor nameplate and application.
Can one VFD be larger than the motor?
A drive one size larger usually runs fine, but a drive several sizes larger can struggle to measure and protect a small motor accurately and tuning becomes less precise. Avoid oversized drives where possible or set the motor protection parameters carefully.
Do I need a braking resistor?
Only if the load regenerates — fast stops on high inertia, downhill conveyors, centrifuges. Try lengthening deceleration first. The resistor must not have a lower resistance than the minimum for your power rating and must be rated for the duty cycle.
How do I connect the drive to a PLC or SCADA over Modbus?
Use the A+ and B- RS485 terminals in a daisy-chain bus with 120 Ω termination at both ends, then set address, baud rate and data format in the communication parameter group. The drive supports standard Modbus RTU.
What does the T1A/T1B/T1C relay do?
It is a volt-free changeover contact (rated 3 A at 250 VAC) that you can configure to signal running, fault, zero speed and similar states to a lamp, alarm or building management system.
Why is the motor running backwards?
Swap any two of the three motor leads on U/V/W (or set the rotation parameter). Change the output side only — never alter the R/S/T input to reverse direction.
Why is my motor getting hot?
Common causes are too low a speed with the internal fan ineffective, excessive carrier frequency, a load above the motor rating, or poor tuning. Check the current against the nameplate and improve ventilation or reduce carrier frequency.
What does -LOC- on the display mean?
The keypad is locked through P7-24. Press and hold ENTER for about 3 seconds to unlock it; it is a lock state, not a fault.
How long must I wait after power-off before wiring?
Wait at least 5 minutes and confirm the charge indicator is off and the DC bus is below about 36 V, because the capacitors hold dangerous voltage for some time after shutdown.
Where can I download the full 300N manual?
The complete SHZK 300N user manual is available as a free PDF in this technical center and on the download page; it contains the full parameter list, wiring diagrams and fault information.
Still need the answer for your exact setup?
Every application is slightly different. If your motor nameplate, load type or fault code is not covered above, send our engineers the details and we will give you the specific setting or fix. You can also keep the full reference document to hand:
Download SHZK 300N Manual (PDF)
Related Technical Guides
Talk to the engineers who built this drive
Stuck on a fault code, wiring or tuning? Our engineers test every SHZK 300N drive before it ships. Send us your setup and we will reply with the exact fix.
Have a specific VFD problem? See our technical troubleshooting guide or contact SHZK support.