How to size a 2000 kVA standby diesel generator for a Saudi commercial mall

## TL;DR

Specifying a 2000 kVA standby generator for a Saudi commercial mall involves managing massive inductive loads from HVAC chillers and non-linear loads from LED lighting and elevators. At this scale, the primary concern is the generator's ability to handle 'Step Loading' without excessive voltage dips that could trip sensitive retail electronics. In Saudi Arabia, compliance with SASO (Saudi Standards, Metrology and Quality Organization) and SEC (Saudi Electricity Company) regulations is mandatory. The sizing heuristic requires calculating the total running kW, applying a 0.8 power factor to find kVA, and adding a 25% safety margin. For a 2000 kVA requirement, a single large-block engine or a synchronized pair (e.g., 2 x 1000 kVA) must be evaluated based on redundancy needs. This guide provides a detailed breakdown of site-specific factors like high ambient temperatures in Riyadh or humidity in Jeddah, ensuring your procurement is robust and compliant.

## Calculating the standby diesel generator duty point

For a commercial mall, the duty point calculation must start with a comprehensive load schedule. A typical mall might have a base load of 1400 kW consisting of lighting, small power, and general services. Using the formula kVA = (running kW / 0.8) × 1.25, we find: (1400 / 0.8) × 1.25 = 2187.5 kVA. However, for a 2000 kVA target unit, we must look at load diversity—not everything runs at once. The duty point must account for the largest single load, usually a centrifugal chiller. If a chiller requires 300 kW to run but has a Soft-Starter that limits inrush to 3x, the generator must provide a 900 kW transient capacity. In the Saudi climate, where 45-50°C is standard, a 2000 kVA 'Standard' generator must be derated by roughly 10-15% depending on the altitude. Thus, a unit rated at 2250 kVA standby might be required to ensure a reliable 2000 kVA output at site conditions.

## Standards and Saudi codes that apply

Procurement in Saudi Arabia is governed by SASO standards, which often mirror IEC and ISO 8528 requirements but include specific testing and certification under the Saudi Product Safety Programme (SALEEM). The SEC (Saudi Electricity Company) has strict codes regarding the connection of private generators to the distribution network, requiring specific protection relays and interlocks to prevent islanding. For the alternator, IEC 60034 is the benchmark. Furthermore, since malls are high-occupancy public buildings, NFPA 110 (Emergency and Standby Power Systems) is frequently mandated by Civil Defence. This governs everything from the generator's start-up time (must be under 10 seconds for life safety) to the location of the fuel tank and exhaust discharge. Ensuring the generator is IECEE certified is now a critical step for customs clearance and legal operation within the Kingdom.

## Common procurement traps for commercial mall

One significant trap is the 'Harmonic Distortion' from VFDs (Variable Frequency Drives) used in mall escalators and HVAC fans. These non-linear loads can cause voltage waveform distortion, leading to overheating of the generator’s alternator. Procurement should specify a 'Permanent Magnet Generator' (PMG) excitation system to provide better motor starting and short-circuit capability. Another trap is 'Altitude Derating'. A mall in Abha (high altitude) will require a much larger engine displacement for a 2000 kVA output than a mall in Dammam (sea level) due to thinner air. Lastly, noise and vibration are critical. A 2000 kVA unit is immensely loud; failing to specify a high-performance acoustic enclosure (75 dB(A) @ 1m) or critical-grade silencers can lead to complaints from neighbouring businesses and potential shutdowns by local authorities.

## Worked example for a 2000 kVA commercial mall

Let’s calculate for a medium-sized mall project in Riyadh:

1. **Identified Running Load**: 1350 kW.

2. **Convert to kVA**: 1350 kW / 0.8 PF = 1687.5 kVA.

3. **Safety Factor (25%)**: 1687.5 kVA × 1.25 = 2109 kVA.

4. **Largest Motor Inrush**: A 250 kW chiller with a VFD (1.5x surge). Surge = 375 kW. Since the VFD limits the surge, it falls within the 2109 kVA capacity.

5. **Apply Site Derating**: Riyadh ambient is 50°C. Assume 10% derate for the engine and 5% for the alternator. Total effective derate ~12%.

6. **Final Selection**: To get 2109 kVA at site, we need 2109 / 0.88 = 2396 kVA (Gross Rating).

7. **Rounding to Ladder**: Looking at the standard ladder (1500, 2000, 2500 kVA), a **2500 kVA** unit is the safest choice to ensure the mall’s 2000 kVA 'Duty Point' is reliably met during peak summer outages.

### Can a 2000 kVA generator handle all mall elevators starting at once?

Usually, no. Elevators have high starting currents. Sizing must account for 'diversity'—the probability of multiple elevators starting simultaneously. For a mall, we typically use a 0.6 to 0.8 diversity factor. Using VFDs on elevators significantly reduces the impact on the generator.

### What are the SEC requirements for standby generators in Saudi Arabia?

SEC requires a formal application for any generator connection. Key requirements include a Four-Pole ATS to ensure neutral isolation and specific protection settings on the breaker to prevent any possibility of power being exported back to the SEC grid during an outage.

### Is it better to have one 2000 kVA generator or two 1000 kVA units?

Two 1000 kVA units in parallel offer 'N+1' redundancy for critical loads (like fire safety) and better fuel efficiency during low-load periods (e.g., at night when the mall is closed). However, one 2000 kVA unit is generally cheaper to purchase and maintain.