## TL;DR

Specifying a 100 kVA standby diesel generator for a Saudi manufacturing facility involves more than matching the nameplate kVA to the load. In Saudi Arabia, compliance with SASO (Saudi Standards, Metrology and Quality Organization) and SEC (Saudi Electricity Company) regulations is mandatory. For a 100 kVA requirement, the primary focus is on the power factor (typically 0.8) and the starting surge of industrial motors. A 100 kVA generator provides 80 kW of prime power, but for standby applications, a 25% safety margin is recommended to ensure longevity and handle transient loads. Furthermore, Saudi Arabia’s ambient temperatures, reaching 50 °C, necessitate a significant derating of the alternator and engine. This guide explains how to calculate the true requirement, ensuring the generator remains stable during the startup of heavy machinery and complies with local IECEE certification requirements for electrical safety and performance.

## Calculating the standby diesel generator duty point

To determine if a 100 kVA unit is sufficient, first aggregate the total running kilowatts (kW) of the essential plant load. The conversion is kVA = kW / Power Factor (PF). For a typical plant with a 0.8 PF, 100 kVA equals 80 kW. However, you must apply a 1.25 safety margin to avoid running the set at 100% capacity continuously, which shortens its lifespan. The formula is: Required kVA = [(Total Running kW / 0.8) × 1.25]. If your running load is 64 kW, the calculation yields exactly 100 kVA. Crucially, you must then check the 'Motor Starting kVA'. If the plant has a large 15 kW motor starting Direct-On-Line (DOL), it can pull 6-7 times its rated current, creating a momentary surge of over 100 kVA. In such cases, the generator must have a high-surge alternator or be upsized to the next ladder step (125 kVA) to prevent voltage dips that could trip sensitive electronics.

## Standards and Saudi codes that apply

All generators imported or used in Saudi Arabia must meet SASO standards and carry the IECEE recognition certificate. The governing international standard is ISO 8528, which defines the performance classes (G1 to G4). For manufacturing plants with sensitive PLC controllers, a G3 class is typically required to maintain tight voltage and frequency regulation. Electrical installation must comply with the Saudi Arabian Grid Code and SEC’s technical requirements for connection to the distribution network, especially regarding the Changeover Switch (ATS). Additionally, NFPA 110 is often referenced for the installation of emergency power systems in industrial settings. The alternator itself must comply with IEC 60034, ensuring it can operate in the high-ambient, dusty environments common in regions like Riyadh or the Eastern Province without insulation failure.

## Common procurement traps for manufacturing plant

A major trap in Saudi procurement is ignoring ambient derating. Most generators are rated at 25 °C or 40 °C. At 50 °C, a generator's effective capacity can drop by 10-15%. A '100 kVA' set might only deliver 85 kVA in a Jiddah summer. Another pitfall is the neglect of fuel quality and storage. High ambient heat can degrade diesel; without proper filtration and cooling, the engine may not hit its rated 100 kVA output. Furthermore, procurement managers often overlook 'Harmonic Distortion' from Variable Frequency Drives (VFDs) within the plant. These non-linear loads cause heating in the generator alternator. If your plant uses many VFDs, the alternator must be oversized (an 'oversized end') even if the kVA rating remains at 100 to handle the extra thermal load without tripping.

## Worked example for a 100 kVA manufacturing plant

Consider a small plastic extrusion line in Dammam. The running load is measured at 60 kW with a power factor of 0.82. Step 1: Convert to kVA = 60 / 0.82 = 73.2 kVA. Step 2: Apply the 1.25 safety margin = 73.2 × 1.25 = 91.5 kVA. Step 3: Check motor starting. The largest motor is a 7.5 kW unit with a Star-Delta starter, requiring approximately 3 times its running kVA during start = 3 × 9.1 kVA = 27.3 kVA. Since the base load (excluding the largest motor) is ~64 kVA, the total momentary peak during that motor's start is 64 + 27.3 = 91.3 kVA. Step 4: Compare with the rating ladder. Since 91.5 kVA and the surge of 91.3 kVA are both below 100 kVA, the 100 kVA standard rating is the correct and safe choice for this application.

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How to size a 100 kVA standby diesel generator for a Saudi manufacturing plant