Data Centre Cooling Plant Retrofit in Singapore

Scenario

A Tier III colocation facility in Jurong, Singapore, retrofitted its chiller plant (serving 12 MW IT load) with variable-speed drives (VSDs) and high-efficiency pumps. Pre-retrofit PF averaged 0.81 due to legacy induction motors and uncorrected lighting loads. Post-VSD commissioning, PF dropped further to 0.78 during partial-load operation—triggering contractual penalties from the utility (SP Group) and raising concerns about transformer derating. Installation space is extremely limited: only 1.2 m² available in the chilled water pump room, with ambient temps consistently at 42°C.

Given Data

• Real Power: 2,150 kW
• Initial Power Factor: 0.78
• Target Power Factor: 0.95
• Voltage: 400 V

Calculation

Using the same formula:

$$ Q_c = P \times \left( \tan(\phi_1) - \tan(\phi_2) \right) $$

• $P = 2150$ kW
• $\phi_1 = \cos^{-1}(0.78) \approx 38.74^\circ \Rightarrow \tan(\phi_1) \approx 0.803$
• $\phi_2 = \cos^{-1}(0.95) \approx 18.19^\circ \Rightarrow \tan(\phi_2) \approx 0.329$

$$ Q_c = 2150 \times (0.803 - 0.329) = 2150 \times 0.474 = 1019.1\ \text{kVAR} $$

The Power Factor Correction Calculator returns:

• Required Reactive Power: 1019.10 kVAR
• Capacitor Bank Size: 1019.10 kVAR

Given space and thermal constraints, a compact, forced-air-cooled 1,050 kVAR static VAR compensator (SVC) with integrated harmonic filtering (tuned to 4.7th order) was specified instead of discrete capacitor steps.

Result and Decision

A 1,050 kVAR SVC unit was installed upstream of the chiller plant MCC. Commissioning verified stable PF ≥ 0.95 across 30–100% load range and eliminated harmonic distortion amplification (THDv < 3.2%). Transformer loading decreased by 12%, deferring a planned 2.5 MVA upgrade. ROI achieved in 22 months.

Lesson

When space and thermal limits preclude conventional capacitor banks, evaluate solid-state reactive compensation (e.g., SVC or STATCOM)—they offer faster response, harmonic mitigation, and higher power density, justifying their premium cost in constrained, mission-critical environments.