Commissioning a Compensation Panel — Briefly
Compensation panel commissioning includes the processes of safely energizing the panel, connecting the current transformer (CT) with correct polarity, programming the reactive power controller (RVC) specifically for the facility, testing the steps one by one, and bringing the cosφ value into the 0.98–1.00 range. Incorrect commissioning leads to serious issues such as capacitor explosion, contactor failure, cosφ shifting to the capacitive side (payback), and TEDAŞ violations. In this guide, we detail the 8-step professional commissioning process we apply in the field.
Preliminary Preparation and Requirements
Site Preparation
- Panel installation test must be completed
- Grounding resistance ≤ 1 Ω
- Current transformer (CT) connected on the main line
- Panel must have IP54 protection class
Required Equipment
- Digital multimeter (TRMS - True RMS)
- Clamp meter (TRMS)
- Phase sequence tester
- Insulation tester (Megger 500–1000 V)
- Thermal camera
- Laptop + USB-RS485 converter (programming)
- Screwdriver set (insulated)
- PPE: insulating gloves (Class 0), face shield, hard hat
Documents
- Panel single-line diagram
- Reactive power controller user manual
- Capacitor values and step table
- TEDAŞ/BEDAŞ project approval
- Facility energy analysis report (before)
Compensation Panel Commissioning in 8 Steps
Step 1: Visual and Mechanical Inspection
- ✅ Cleanliness inside the panel (dust, chips, leftover screws)
- ✅ Check that all connection screws are tight (to torque)
- ✅ Dull-free clean brightness of busbar connections
- ✅ Capacitor outputs are not deformed
- ✅ Contactor mechanical hand test (manual pull-in)
- ✅ Fuse nominal current ratings are correct
- ✅ Labeling (kVAR value for each step)
Step 2: Grounding and Insulation Test
- Measure panel body grounding resistance → ≤ 1 Ω
- Phase-to-ground insulation test (with 500 V DC) → ≥ 100 MΩ
- Neutral-to-ground insulation test → ≥ 100 MΩ
- Phase-to-phase insulation test → ≥ 100 MΩ
- Capacitor measurement quality (with LCR meter) → nominal ±5%
Step 3: Current Transformer (CT) Connection
This is the most critical step. Incorrect CT connection causes the controller to operate in reverse.
- CT location: On the load side of the main line, BEFORE all compensation capacitors
- Check CT ratio: e.g., 1000/5 → must be entered correctly into the controller
- Polarity: P1 faces the source, P2 faces the load
- S1 → controller I+ input
- S2 → controller I- input
- CT secondary cables must be short-circuited (dangerous when open!)
- Verify secondary current with a clamp meter
Step 4: Reactive Power Controller Programming
Varies by brand; common parameters:
| Parameter | Recommended Value |
|---|---|
| CT ratio | According to the installed CT (e.g., 1000/5) |
| Target cosφ | 1.00 (to avoid going capacitive) |
| Tolerance | 0.005 (operate within ±0.005) |
| Mode | Auto (automatic) |
| Connection type | 3-phase 4-wire (TT or TN) |
| Number of steps | Number of steps available in the panel |
| Step power type | C/k ratio (smallest step/CT current) |
| Switching type | Rotational |
| Minimum waiting time | 30–60 seconds |
| Capacitor discharge time | 60–180 seconds |
| Harmonic protection (if any) | THD-V > 5% → disable the step |
Step 5: First Energization
- Ensure the fuse in front of all capacitors is open
- Close the main switch
- Controller reads voltage → 3-phase voltage must appear on the screen (close to 220 V)
- Reads load current → compare with clamp meter
- Difference between displayed cosφ and actual cosφ must be at most 0.02
- If cosφ is read in reverse (e.g., inductive instead of capacitive) → CT polarity is wrong!
Step 6: Manual Step Test
Set the controller to manual mode and for each step in order:
- Close the Step N fuse
- Switch the step on with a manual command
- Wait 15 seconds and listen:
- Click (contactor healthy)
- Hum (not suitable → replace contactor)
- Explosion / spark (capacitor failure → replacement)
- Measure step current with a clamp meter (nominal value ±5%)
- Switch the step off again manually
- 60-second discharge waiting time
- Test the other steps in sequence
Step 7: Automatic Mode and Performance Check
- Set the controller to AUTO mode
- Wait until the system warms up with the load (~30 minutes)
- Verify cosφ has reached the 0.98–1.00 range
- Measure THD-V (THD > 5% → detuned reactor missing!)
- Are step transitions smooth (rotational algorithm)?
- Check automatic step shedding under overload
Step 8: Documentation and Handover to the Customer
Performance Report should include:
- Comparison of cosφ before and after commissioning
- Active/Reactive power measurements (24 hours with a TRMS analyzer)
- Estimated annual savings (TL)
- Step test results (current, temperature)
- Thermal camera scan (contactor and capacitor temperatures)
- 12-month performance monitoring commitment
Common Mistakes
| Mistake | Symptom | Solution |
|---|---|---|
| CT polarity reversed | cosφ is read capacitive | Swap S1-S2 |
| CT location wrong | Controller reads capacitor current | Move CT to the load side of the main line |
| Target cosφ 0.98 | Payback penalty | Set target to 1.00 |
| Reactor missing (THD>5%) | Capacitor explodes | Add detuned reactor |
| Steps switch in rapid succession | Controller delay insufficient | Min waiting 30–60 s |
| Wrong C/k | Step switches on for very small load | C/k = smallest step / (CT × √3) |
DOA Enerji Compensation Panel Commissioning Service
DOA Enerji provides on-site commissioning service for Schneider, ABB, Frako, Iskra compensation panels. A package is offered as 7-day energy analysis → correct capacity calculation → commissioning → 30-day performance monitoring. A 2-year performance guarantee is standard.
Frequently Asked Questions
How many hours does commissioning take?
For a standard 50–200 kVAR panel, 4–6 hours. For detuned panels above 400 kVAR, one full working day is typical.
Will the facility’s electricity be cut during commissioning?
During the connection of the compensation panel, the main power must be switched off (~15–30 min). Commissioning tests are performed while the facility is operating.
Why should cosφ be 1.00?
If the target is 0.98, load fluctuations will occasionally drop cosφ below 0.97 and TEDAŞ will issue a penalty. When the target is 1.00, the penalty-free band becomes safe. Going above 1.00 to the capacitive side also requires a separate penalty; the controller prevents this automatically.
How much savings will I see after compensation commissioning?
In typical facilities, 10–25% bill savings are expected. The first bill may show it halfway through the month; full savings are clearly seen over a 30-day period.
How often should maintenance be performed?
Every 6 months: 1 thermographic inspection + controller log analysis + cleaning. Once a year, detailed maintenance (capacitor capacitance measurement, contactor cleaning) is mandatory.