### Stationary UPS Sizing Calculations – Part One

As we stated in the previous article “Evaluation Criteria for Selecting an UPS-Part One”, where we explained the (8) steps for Evaluation Criteria for Selecting an UPS and left Step#3:  Determine the power requirements to be discussed later in detail. Today, we will do this.

 Stationary UPS Sizing Calculations

 The sizing calculations include: The UPS KVA sizing calculations,Rectifier sizing calculations,Inverter sizing calculations,The Battery sizing calculations.

 1- The UPS sizing calculations

Step#1: List All the UPS Loads

Make a list of the equipment/load that needs to be supplied from UPS.

Step#2: List for Each Equipment/Load, the Voltage, Number of Phases, And Frequency

In existing installations:

Two methods are available:

Method#1: for each equipment/load, get the voltage, number of phases, and frequency from the equipment nameplate.

Method#2: for each equipment/load, get the voltage by measuring it and you can easily determine the number of phases, and frequency by experience.

When the installation is in the planning stage or when the measurements cannot be taken:

For each equipment/load, get the voltage, number of phases, and frequency from equipment manufacturers' data.

At the end of step#2, the table will be as follows:

 s/n Loads to be supplied from UPS Voltage Nos. of phases frequency 1 Load 1 2 Load 2 3 Load 3 …. ….. …. …... n Load n

 Step#5: Segregate the Loads (Non-Motor Loads & Motor Loads) At the end of step#5, the table will be as follows:

 Step#6: Determining Load Power Factor and KW Demand   In existing installations: The load power factor should be determined by actual measurements using a power factor meter.   When the installation is in the planning stage or when the measurements cannot be taken: To calculate the load power factor, the kVA and power factor of the individual loads should be obtained by one of the following methods: Method#1: From the owner‘s/operator’s manual available from the equipment manufacturer Method #2: Estimated from the data in table-1 Method #3: If the above methods not available, estimate it as 0.85    Table-1 Typical load power factors and inrush requirements   At the end of step#6, the table will be as follows:

In the next Article, we will explain the Rectifier, Inverter & Battery sizing Calculations. So, please keep following.

Subject Of Pervious Article

Article

Applicable Standards for UPS Systems

What is a UPS?

Why do we need a UPS?

UPS Rating

Classification of UPS:

1-Voltage range,

2-No. of phases,

3- Mobility,

4- Technological design,

5- Physical Size/capacity,

6- Form factor/ configurations:

6.1- “N” System Configuration

Classification and Types of UPS – Part Two

6.2- “N+1” System Configuration, which includes:

• Isolated Redundant Configuration (N +1)
• Parallel Redundant Configuration (1+1)
• Parallel Redundant Configuration (N +1)
• Parallel Redundant Configuration (N +2) and so on

6.3- Parallel Redundant with Dual Bus Configuration (N+1 or 1+1)

Classification and Types of UPS – Part Three

6.4- Parallel Redundant with STS Configuration

• Parallel Redundant Configuration (1+1) + STS
• Parallel Redundant Configuration (N+1) + STS

6.5- System plus System 2(N+1), 2N+2, [(N+1) + (N+1)], and 2N

Classification and Types of UPS – Part Four

7- According to UPS Topology

7.1 Off-line or Standby UPS,

7.2 Line Interactive UPS,

7.3 Standby-Ferro UPS,

7.4 Online Double Conversion UPS,

7.5 The Delta Conversion On-Line UPS.

8- According to UPS Distribution Architecture

8.1 Centralized UPS Configuration,

8.2 Distributed (Decentralized) UPS Configuration,

8.2.1 Distributed UPS-Zonewise Configuration

8.3 Hybrid UPS Configuration.

Conventional (Monolithic) Vs Modular UPS System:

• Deploy UPSs in parallel,
• Deploy UPSs in Series,
• Use modular UPS products.

Three Basic Configurations Of Mains And Bypass For A UPS System:

• Single mains,
• Single mains without bypass,
• Dual mains.

9-According to Use of transformers with the UPS

• Transformer based,
• Transformer less UPS,
• Transformer less UPS with external input/ output transformer.

Transformer Arrangements in Practical UPS Systems:

1-Transformer options for the “single mains” configuration

2-Transformer Options for the “Dual Mains” Configuration

3- Transformer options for “single mains without bypass”

Components of Online Double Conversion UPS:

1- Rectifier,

2- Inverter,

3- Energy Storage system:

3.1 Battery

### Components of Online Double Conversion UPS– Part One

3.1.1 Battery Configurations

• Serial Strings,
• Parallel Strings.

3.1.2 Battery Size and Location

3.1.3 Battery Transition Boxes

3.1.4 Battery Monitoring

3.2 Energy Storage System – Flywheel

3.3 Energy Storage system – Super Capacitors

3.4 Hydrogen Fuel Cells

4- Static switch

Earthing Principles of UPS Systems

Evaluation Criteria for Selecting an UPS:

Step#1: Determining the need for an UPS,

Step#2: Determining the purpose(s) of the UPS,

Step#3: Determining the power requirements,

Step#4: Selecting the type of UPS,

Step#5: Determining if the safety of the selected UPS is acceptable,

Step#6: Determining if the availability of the selected UPS is acceptable,

Step#7: Determining if the selected UPS is maintainable, and

Step#8: Determining if the selected UPS is affordable.

Example: Selecting an Uninterruptible Power Supply (UPS)

UPS System Ratings and Service Conditions:

• First: from IEC 60146-4
• Second: according to American standards