CES GX RACK 10 kVA UPS: Parallel Operation

This document outlines the procedure for operating CES GX RACK 10 kVA Uninterruptible Power Supply (UPS) units in parallel mode. It details the necessary connections and checks for a stable and reliable power system.

Introduction to Parallel Operation

The CES GX RACK 10 kVA UPS units can be configured for parallel operation to increase power capacity or provide redundancy. This guide focuses on the setup and verification steps for such configurations.

Manufacturer: Centrum Elektroniki Stosowanej CES sp. z o. o.

Address: 30-732 Kraków, ul. Biskupińska 14

Contact: tel.: (012) 269-00-11, fax: (012) 267-37-28, e-mail: ces@ces.com.pl, www.ces.com.pl

Version: U/CES_GXR_10.0/J/v01

Input and Output Connection Diagram

This diagram illustrates how to connect the input and output power lines for UPS units operating in parallel. It shows two UPS units, each with separate Line (L), Neutral (N), and Protective Earth (PE) input and output terminals. These are connected via individual switches to a common power source and to the load. The diagram emphasizes the use of switches for control.

Communication and Load Sharing Connections

For parallel operation, UPS units require communication links and load sharing connections. The diagrams show how these are established:

Communication Connection Diagram: Depicts three UPS units connected via dashed lines. Red dashed lines represent the parallel communication links, enabling the units to synchronize and share operational status.
Load Sharing Diagram: Green dashed lines in the communication diagram indicate the connections for load sharing, ensuring that the power demand is distributed evenly among the parallel UPS units.

Communication Cable: A dedicated cable with DB9 connectors is used to link the UPS units for parallel communication.

Load Sharing Cable: A specific cable is used to connect the load sharing ports between UPS units.

UPS Rear Panel Description

The rear panel of the CES GX RACK UPS features several ports and terminals essential for connection and configuration:

INPUT Terminals: L (Line), N (Neutral), PE (Protective Earth) for connecting to the AC power source.
OUTPUT Terminals: L (Line), N (Neutral), PE (Protective Earth) for connecting to the load.
INPUT BREAKER: An internal switch for the input power.
BATTERY CONNECTOR: For connecting external battery cabinets.
INTELLIGENT SLOT: For optional communication cards.
CONTROL OUTPUT
SIGNAL PORT
USB Port
RS 232 Port
EPO (Emergency Power Off) Port
TERMINAL STRIP: Used for input power connections.

Installation and Setup Procedure

Note: Before operating devices in parallel, it is necessary to connect a battery cabinet to each of them. Refer to the instruction manual: CES_GX_10000R_SZAFA_BATERYJNA_(U_CES_GXR_10.0_B_v01).

Step 1: Connecting the UPS Input

Ensure all switches on battery cabinets and the UPS are in the OFF position.
Unscrew the screws securing the terminal strip cover and remove the plastic plate.
Use a cable with a conductor cross-section of at least 10 mm². Extension cords are not recommended.
The device must be connected to a network with a protective conductor (e.g., TN-S). Connect the PE conductor first.
Connect the power cables only to the UPS terminal strip; do not connect to the power source yet.
Repeat this procedure for each UPS unit intended for parallel operation.
Install a switch between the power source and the input of each UPS (refer to the 'Input and Output Connection Diagram' on page 1).

Step 2: Connecting the UPS Output

Connect the output cables of each UPS using cables with a conductor cross-section of at least 10 mm².
The output cables from each UPS must be connected to a switch.
Subsequently, each UPS output switch must be connected to a main switch.
The main switch should be connected directly to the load (refer to the 'Input and Output Connection Diagram' on page 1).

Step 3: Connecting the Communication Cable

Use the provided cable to connect the UPS units in a closed loop.
Make these connections according to the 'Communication Connection Diagram' on page 2.

Step 4: Connecting the Load Sharing Cable Between UPS Units

First, unscrew the screws securing the cover of the load sharing ports between the UPS units.
Using the provided cable, connect the UPS units to form a closed loop for load sharing.
Make connections according to the 'Communication Connection Diagram' on page 2.
After making the connections, screw the port cover back on.

Step 5: Checking the Bypass Line Voltage

Ensure all switches (battery, input on the UPS rear panel, input between the power source and UPS, and output) on each UPS are in the OFF position.
Connect the UPS to the power supply.
Switch to the ON position the battery switches, the switches between the power source and the UPS, and the input switches on the rear panel of each device. The UPS will start up and operate in bypass mode.
Using a multimeter, measure the voltage difference on the output phase connection between each device (e.g., UPS 1 output phase to UPS 2 output phase).
If the measured voltage difference is less than 1V, the devices have been correctly connected.
If the measured voltage is greater than 1V, check if the power cables are connected correctly (e.g., phase and neutral wires are not swapped).

Step 6: Checking Voltage for Online Mode Operation

Before switching the UPS from bypass mode to online mode, ensure that the parameter PAR001~PAR002 (for two UPS units) or PAR001~PAR003 (for three UPS units) is displayed on each connected device.
If this parameter is not displayed on any unit, verify that the parallel communication cables and power distribution have been connected correctly.
If the parameter is displayed correctly, proceed with starting up the devices.
Start up each UPS sequentially by pressing the ON/ENTER button on the front panel for approximately 1 second.
The device will signal with a short beep that startup has begun. After about 5 seconds, it will enter normal (online) operating mode. The display will show voltage readings (e.g., 230 Vac for INPUT and OUTPUT), and a green LINE LED will illuminate.
After startup, measure the output voltage of each UPS (between phase and neutral). The difference between measured voltages should not exceed 2V (typically 1V).
If the difference is greater than 2V, check the parallel communication cables and power distribution. If the issue persists, contact the service department.

Step 7: Powering On Devices Connected to the UPS

Before switching the output breakers to the ON position, turn OFF each of the UPS units. Press and hold the OFF/ESC button on the front panel for approximately 1 second. The connected devices will operate in bypass mode.
Then, switch all output breakers to the ON position. The devices connected to the UPS output are now powered.
The final step is to start up each UPS sequentially by pressing and holding the ON/ENTER button for approximately 1 second.

UPS Display Indicators

The UPS display provides real-time information. In normal operation, it typically shows the input and output voltages (e.g., 230 Vac). Indicators for INPUT, OUTPUT, BYPASS, I/P (Input), and O/P (Output) are present. A green LINE LED illuminates when the UPS is operating in normal online mode.

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