Armature voltage: tell it apart from the supply and the rating
Many buyers ask “is a higher DC voltage always better”. First separate two things: the armature voltage (fed to the armature circuit, it sets speed and torque) and the excitation voltage (fed to the field winding; on separate excitation it is a separate 180V). This article is about the armature voltage, whose standard steps are 160V / 400V / 440V, matching different supplies and drives.
Z4 series armature voltage comparison
| Armature voltage | Typical supply | Feature | Common use |
|---|---|---|---|
| 160V | Low-voltage DC / battery | Lower voltage, higher current; thicker cable and switchgear | Mobile plant, test bench, low-voltage DC bus |
| 400V | 380V AC rectified | Standard industrial supply rectification, most common | General industrial drive |
| 440V | 440V DC / higher rectification | Lower current, smaller cable, better for larger power | Rolling mill, crane, continuous line |
How to choose: four steps
- Check the supply: 380V AC → use 400V; an existing 440V DC bus → use 440V; low-voltage / mobile → use 160V.
- Power and current: the larger the power, the better high voltage (440V) saves cable and switchgear; small power often uses 400V to keep the drive simple.
- The drive: the rectifier / drive output must cover the chosen armature voltage.
- Speed: at the same power, a different voltage shifts the rated speed and the weak-field range - cross-check against the Z4 series speed steps.
Do not ignore the excitation voltage (separate 180V)
The Z4 series is separately excited; the standard excitation voltage is 180V, fed by a separate exciter. It is unrelated to the armature voltage but still matters for running: above the rated value it reduces reliability, and if the field is broken you should connect about 7× the cold field-winding resistance as a discharge resistor. When specifying, send us both the armature voltage and the excitation voltage.
FAQ
Q: Is 440V always better than 400V?
A: Not necessarily. Higher voltage saves cable and switchgear but needs a matching supply and drive; if the site only has 380V AC, 400V is simpler.
Q: Can you make a non-standard voltage?
A: Yes, the Z4 series can be built to your supply, though it adds lead time and cost - prefer a standard step.
Q: Does changing the voltage change the speed?
A: Yes. The armature voltage sets the top of the constant-torque range; after a change you must re-check rated speed and the weak-field range.
Q: How do I send my duty for selection?
A: Provide the supply voltage, load torque, speed range, duty (S1/S5 etc.) and mounting; we will pick the frame and voltage with our Z4 selection.