Harmonic compliance usually arrives as somebody else's problem. A utility study flags the point of common coupling, an EPC specification drops IEEE 519 into a scope of supply, or a transformer runs hot for eighteen months before anyone puts a meter on it.
Then the conversation turns commercial: whose equipment is producing the distortion, and whose vendor pays to fix it.
That conversation is usually the wrong one. A six-pulse rectifier draws the same non-sinusoidal current whether it sits behind a Triol nameplate or anybody else's. The 5th, 7th, 11th and 13th harmonics are a property of the conversion topology, not of the brand, the firmware or the control method.
That holds for six-pulse front ends, which is most of the installed base. A 12-pulse drive or an active front end has a different harmonic signature, and a different filter conversation.
Figure 1. A six-pulse front end distorts the supply current the same way regardless of who built the drive.
Triol has used passive filters as options in the AT24 and AK06 series for over ten years. The PF01 series takes that hardware out of the drive cabinet and makes it free-standing: devices that can be used with Triol converters as well as converters and other power devices from various manufacturers.
The power circuit is passive, inductors and capacitors in an L-shaped scheme, sized against the grid and the load. No communication link with the converter, no firmware handshake, nothing to set on the drive side.
What a selection actually depends on
Electrical inputs, not commercial ones.
| Selection input | Value or range |
|---|
| Supply voltage and frequency | 400, 415, 480, 600 or 690 V, at 50 or 60 Hz |
| Rated current or power of the converter | PF01 covers 90 to 876 A across 34 standard models |
| Presence or absence of a DC-link choke | Decides whether the output choke option is needed |
| Mains unbalance and network impedance | Up to 1% unbalance, impedance of 1.5 to 6% |
| Minimum operating load | 70 to 100% in the base version, from 30% with the half power mode |
| Target THDi | Below 5%, below 8% or below 10% |
| Ambient temperature and enclosure | +1 to +40°C and IP00, IP23 or NEMA 3R as standard; extended ranges and IP54 or NEMA 4 as options |
| Cable entry | Bottom or side |
Table 1. What a PF01 selection is based on.
The one drive-side detail that matters: the DC-link choke
There is exactly one thing about the converter that changes the order code, and it is not the brand. It is whether the converter already has a choke in its DC link.
Plenty of six-pulse drives ship without one, particularly at the budget end of the market and on older installations.
For those, PF01 offers an output choke (power circuit code 01), and for a load without a DC-link choke in a thyristor rectifier there is a dedicated filter operating mode. Either can be specified at order or fitted later during operation.
Figure 2. The DC-link question decides one code position. Everything else comes from the site.
Sizing by current, not by nameplate
Thirty-four standard models cover 90 to 876 A across three supply groups. If the converter sits inside that window and inside 400 to 690 V at 50 or 60 Hz, there is a standard PF01 for it.
| Supply | PF01 current, A | VFD power, kW | VFD power, hp | Models |
|---|
| 380 to 440 V, 50 Hz | 160 to 880 | 90 to 500 | 125 to 700 | 11 |
| 460 to 480 V, 60 Hz | 140 to 700 | 90 to 500 | 125 to 700 | 11 |
| 570 to 690 V, 50 Hz | 100 to 620 | 90 to 630 | 125 to 850 | 12 |
| Full series range | 90 to 876 | 90 to 630 | 125 to 850 | 34 |
Table 2. Standard coverage of the PF01 series.
PF01 is designed against EN 61000-2-2, EN 61558-2-20, EN 60831-3, UL 61800-5-1 and CSA C22.2 No. 274, which is what allows it to meet the stringent requirements of IEEE 519.
The filters are certified and approved by UL and CE.
| THDi below 5% | THDi below 8% | THDi below 10% |
|---|
| Superior harmonic distortion reduction | Balanced harmonic distortion reduction | Moderate harmonic distortion reduction |
| Highest protection and power stability | Suitable for standard industrial applications | For less critical applications |
| Ideal for high-precision and sensitive systems | Optimal balance of cost and efficiency | Suitable for high-power grid applications |
Table 3. Three THDi tiers, one platform.
Those figures are declared at 70% load and above, for mains unbalance of 1% and mains impedance of 1.5 to 6%.
A THDi number quoted without those conditions attached is a number, not a guarantee.
Loads that will not hold still
Retrofit sites rarely run at nameplate, and a passive filter tuned for full load drifts as the load moves. The basic PF01 covers 70 to 100%.
Below that, Triol offers a patented solution that delivers the declared THDi under varying load conditions while reducing total power consumption by up to 30% of the nominal value for extended periods.
With the output choke option, our solutions work with loads from 30% to 100% of the VFD rated power.
Figure 3. THDi against load for the three operating modes.
Proof at the point of common coupling
The argument that started this article ends with a measurement, so PF01 can carry the instrument that produces it.
The optional power meter, DATAKOM, Schneider, Acuvim or the customer's own, records voltage and current THD, individual harmonics, unbalance, crest factor, K factor and power quality events with time stamps, shows them on the cabinet HMI, and transmits to SCADA over RS-485 Modbus RTU, Ethernet Modbus TCP or PROFIBUS.
In a compliance dispute, that log is the difference between an opinion and a record.
Running third-party drives and facing an IEEE 519 limit? Send us the supply voltage and frequency, the converter current, whether it has a choke in the DC link, the minimum operating load and the site conditions. Brand not required.
Request a filter selection or a quotation for PF01.
