Administrative FAQ
1. Can I buy samples for immediate delivery?
2. Can I buy ex-works (I have my own courier/agent)?
3. Is there a minimum order quantity?
4. I would like to promote/market/distribute this technology in my area.  What do I do?

Technical FAQ

1. What is power factor and why is it important?

Power factor is the ratio of active power (measured in W) to apparent power (measured in VA) in a line and is a measure of the current capacity utilization of the distribution circuits (the higher the better). With linear loads and sinusoidal voltage and current waveforms the power factor equals to the cosine of the phase angle between the current and voltage vectors. All practical loads employ a magnetic circuit (motors, transformers etc) which introduces inductance in the circuit and results in out-of-phase voltage and current vectors. The inductive current circulates without producing useful work between the source and the load and effectively reduces the distribution network capacity (limited by the wiring cross-section area). In addition, the higher current results in higher conduction losses and may falsely trip protective devices.

2. Which power factor measurement and compensation method does the PFC1 use?

The PFC1 measures the phase angle between the load current and voltage vectors and corrects the measured inductive power factor by switching in and out of the line compensating capacitor banks.

3. What type of capacitor bank switch can be used with the PFC1?

Solid state relays (SSRs) and any mechanical switch such as contactor relays.

4. What are the considerations in selecting the capacitor bank switch?

Solid state relays (SSRs) must be of the synchronized (or zero-crossing) type and use a suitable dimensioned heatsink. The zero-crossing property ensures that the capacitors are switched in when the line voltage equals the capacitor voltage thus eliminating capacitor inrush current and extending capacitor life. The capacitor discharging resistors are for safety reasons only and can be any suitable value giving minimum heat dissipation while the bank is connected to the line.

Contactors must be of the special two stage design limiting capacitor inrush current at bank switch-in. The capacitor discharge resistors must be sized to optimally bring down the capacitor voltage (using the PFC1 controller capacitor time-out protection feature) before a possible switch-in to minimize the average inrush current and keep heat dissipation at acceptable levels. Also, as contactors are slow devices they cannot be driven at the faster measurement times of the PFC1.

5. How are PFC1 faults handled?

During a fault the PFC1 outputs are deactivated and the error condition clears automatically after its cause has been removed.

6. What are the considerations in setting the PFC1 measurement time?

The PFC1 measurement averaging and sampling time can be set to 1, 2, 3 and 5 seconds. Choosing this time depends on the monitored load dynamics and the required response time.

The choice of bank switch type is also important as switching mechanical relays at high rates affects their reliability and service life. Solid state relays (SSRs) are not affected by the choice of measurement time.

7. Why use the PFC1 initial output setting facility?

The facility is useful for compensating loads approximately while the first measurement is being performed. This allows for "kickstarting" load compensation to a given level and so converge faster to the high power factor state (better than 0.95).

8. How can the capacitor bank be sized for a given load?

A simple and practical method is to provide the load active power in capacitor reactive power in three steps. As an example, a 15 KW load can be compensated with three 5 KVAr capacitor banks up to a worst case power factor of 0.7.

9. What is the operating control sequence of the PFC1?

On activation (current higher than 10 % of range) the outputs are initialized as set by the DIP switch until the first measurement is completed. From then on and at every new measurement the outputs remain unchanged until the next measurement is complete if the measured power factor is above 0.95. The outputs are incremented (the next step is activated) for inductive power factors below 0.95 and the output protection time-out has elapsed. Correspondingly the outputs are decremented (the highest step is deactivated) for capacitive power factors below 0.95.

10. Can one set of PFC1 outputs drive the capacitor banks and the other signal a PLC?

Yes. The 24 VDC and contact outputs are galvanically isolated from each other and can be used in different circuits.

11. Why deactivate the PFC1 at currents less than 10 % of range?

Compensating small loads may cause more problems than is worth. In the typical case the first step capacitor will overcompensate and the system will toggle between capacitive power factor (capacitor in) and inductive power factor (capacitor out) with the capacitive current being a lot higher than the load current (the one to be corrected).

12. Which line voltages does the PFC1 cover?

Currently the PFC1 is available for 3x400 VAC lines.  Please contact us for other voltages.

13. Why is the PFC1 not front panel mountable like most other power factor controllers?

The PFC1 is designed for simple (up to three step), low-end applications such as power factor compensation for a domestic lift. On the other hand front panel mountable controllers address more demanding applications which require more compensating steps, set-up parameters and monitoring functions.

The PFC1 is designed to be very simple to install (only two parameters to set-up via the DIP switch, no front panel interaction needed) and requires the absolute minimum of external components (the current transformer, the capacitor bank switches and the capacitor banks themselves) to provide fast (1 to 5 seconds process time) power factor compensation for a variable load.

Also, being DIN rail mountable allows it to be enclosed in a high IP rated enclosure for use in adverse environments.

Administrative FAQ

1. How can I buy samples for immediate delivery?

By contacting us with your special instructions.  We make every effort to have sampling quantities of standard models ex-stock for quick worldwide delivery.

2. Can I buy ex-works (I have my own courier/agent)?

Yes, by contacting us with your requirements and instructions.

3. Is there a minimum order quantity?

No, but note that shipping/handling charges become proportionally higher with smaller orders.

4. I would like to promote/market/distribute this technology in my area.  What do I do?

Contact us!