Capacitors Vs. Hybrid
The different types of power factor units are capacitor based, hybrid, and full SVG. Each type of unit has clear advantages and disadvantages, but when a system is put in the right scenario, the benefits outweigh the other system drawbacks. A site visit by one of our technicians will determine which system or combination of systems will best suit the site requirements.
| Feature | Capacitor Based | Hybrid System | Full Active SVG |
|---|---|---|---|
|
Cost Per Unit
|
Low
|
Medium
|
High
|
|
Leading or Lagging Power Factor Units
|
Lagging
|
Both
|
Both
|
|
Exact kVAr Requirements
|
|
|
|
|
Real Time Compensation |
|
|
|
|
Capacitor Type |
Dry |
Electrolytic & Dry |
Electrolytic |
|
Capacitor Zero Switching |
|
|
|
|
Heat Generated |
Low |
Low |
Med-High |
|
Ease of Future Additions/Flexibility |
|
|
Difficult |
|
Cost of Expansion |
Low |
Low |
High |
|
Still Works With Partial Loss of Power |
|
|
|
|
Repaired/Maintained on Site |
|
|
|
|
Improves System Resonance |
Minimal |
Medium |
|
Advantages of a Capacitor Based System:
- Easily expandable - future proof
- Cooler & quieter operation
- Able to handle dirtier environments without adverse effects
- Easy to service with readily available parts, can be serviced by most industrial electricians
- Reliable & long service life
- Effective performance can still be achieved if individual components fault
- Thyro switched steps can react within 20mS to changes to load
- Can be serviced from the front, without taking the system off line
- Can be installed against a wall
- Simple installation and commissioning
- Only need one CT in MSB
Advantages of Static Var generator (SVG) and Active Harmonic Filters (AHF):
- Very fast response, and corrects each phase independently
- Corrects harmonic frequencies (up to 13th for SVG, and 50th for AHF)
- Can correct leading and lagging power factor to 0.99
- Comes in wall mounted configuration up to 100kVar (or 150A AHF)
- Some parts are replaceable in NZ by our technicians
Disadvantages of a Capacitor Based System:
- Standard switching systems respond slower than electronic systems
- can be susceptible to certain harmonics damaging capacitors
- Large and heavy
- Can only correct all phases at the same rate
- Cannot correct leading power factor
- Cannot correct harmonic frequencies
Disadvantages of Static Var generator (SVG) and Active Harmonic Filters (AHF):
- Expansion past one unit requires a separate HMI controller
- Needs 3 CTs in MSB
- At full load, the fan noise can be too loud for quiet environments
- Create more heat than capacitor based systems, needing extra air-conditioning for large units
- Normally need an on-site commissioning by an expert technician
- Cabinet mounted units need rear and front access and ventilation
- Requires a clean environment
- Complete shutdown of unit for any small failure
- Needs expert repair technicians or return to factory for repairs
