Industrial UPS System
Complete Power Solution with
Maximum Protection
The system consists of rectifier / charger, inverter, static bypass, maintenance bypass, rectifier isolation transformer, inverter isolation transformer, bypass line isolation transformer, automatic line stabilizer, DC distribution, AC distribution, controls and monitoring. The AC output of the inverter is connected to the critical load, the storage battery is connected between the inverter input and rectifier / charger output through a battery isolation MCB. The normal AC input power is connected to the rectifier; the bypass circuit also takes power from the same power source to provide power for the critical load during bypass operation when the system is in maintenance mode.

Industrial UPS Concept
Industrial UPSs are regarded as fully customized power supply systems for rugged environments and designed particularly to safeguard critical loads in industrial applications where voltage transients, created by degraded mains supply, can seriously damage both UPS and the critical load. Industrial UPS Systems are fully flexible and customizable and designed for active–on line installation between the power source, by-pass source and critical load where the inverter delivers regulated AC voltage and frequency to the load and rectifier delivers regulated DC voltage / current to the DC load at all times without interruption.
The power conversion process isolates the critical load from the normal mains disturbances and isolates the mains from load induced reflected harmonics affecting other loads connected to the input mains feeder. The rectifier converts AC power into DC to charge maintenance free lead acid or nickel cadmium batteries; it also provides the necessary DC for continuously rated capacity of the inverter. IGBT semiconductor modules are used in PWM inverter and the control logic creates the precise sinusoidal output waveform with a very low harmonic content. Thyristor semiconductor modules are also used in rectifier for reliable operation.


Industrial UPS Systems are primarily designed to meet requirements for the applications;
  • Oil and gas offshore and onshore,
  • Petrochemical,
  • Chemical,
  • Power and Substations
  • Production process plants
  • Offshore installations
  • Pipeline control centers
  • Airport, avionics and airfields
  • Railways and metro lines
  • Hospitals and healthcare
  • Security and Alarm equipments
  • Defense
Block Schema
High Performance at Nonlinear Loads
Inverter output encompasses 6 IGBT modules, boosting the instant power capacity of GESS Online UPS systems by double fold with comparison to regular systems. This feature allows GESS to handle higher capacity loads (inrush currents) with smaller capacity devices. In addition, switching at high frequency - 20 KHz. - keeps the output sin wave (THD) undistorted providing reliable solutions for nonlinear loads.

Load Security Against Mains Failure
Load is fully isolated with galvanic transformer. Therefore, in circumstances where the load is likely to be affected by a very large variation in its power supply, a transformer-based UPS provides a safer and more robust solution than transformer-less technology simply because its size and construction afford some inertia between the input and output waveforms, with no additional electronic filtering required. For utmost critical applications like the ones in oil & gas or health care sectors, redundancy on the rectifier side (direct connection) and on the inverter side (via static transfer switch) is highly recommended. Our Static Transfer Switch topology offers 3-input design: The 2 inputs are for the UPSs and 3rd input being utilizable as common bypass line for UPSs or as the 3rd redundant line input which is seen as the most important advantage against load sharing systems.

Load Security Against Battery And Rectifier Failure
Load is fully isolated with galvanic transformer. In case of battery or rectifier failure the distorted DC current is filtered out by the transformer, so there is no need to employ additional electronic filtering. In addition due to transformer based architecture less number of electronic components are employed, which brings higher mean time between failure (MTBF) to the system..

Modular Architecture
UPS systems have a modular architecture, meaning that they're built with a number of electronic cards to control each unit instead of a large, single motherboard; thus it would be enough to replace particular PCB to fix the device in case of a failure. It can be translated into significantly lower spare part cost and shorter maintenance time.

Ideal Solution For Industrial Uses
Transformer-based devices are ideal for sites that experience heavily polluted mains supplies –particularly industrial, rural and complex infrastructure locations, such as hospitals, petroleum plants, airports etc. In these circumstances, any UPS would be expected to offer dependable long-term protection from repetitive transients and electrical noise.

Battery Effeciency
Unlike transformer-less systems, transformer based online UPS systems use fewer number of battery sets to feed the load due to its unique architecture. Therefore battery sets get charged evenly and at optimum rates to maximize the battery life time and reduce long term battery replacement cost. Our Industrial UPS Systems come with 110 VDC, 125 VDC, 144 VDC, 220 VDC, 264 VDC or 360 VDC bus bar ratings with up to 1000 Amp charging capacity.

Longterm Operational Efficiency
PMI transformer based, double conversion online UPS systems provide longer operational efficiency as transformer-less UPS systems bring operational risks and downtime due to malfunction especially for industrial uses where voltage transients, created by degraded mains supply, can seriously damage both UPS and the load.

Technical Specifications

Rectifier Block

The rectifier is SCR controlled AC/DC rectifier with input isolation transformer and with automatic constant voltage and constant current ability. It comes with 6 Pulse or 12 pulse design options depending on user requirements. The advantages of employing 12 pulse rectifier in industrial UPS systems are to have lower THDi (<10%) and higher pf at input (>0.9) as well as to secure redundancy since 12 pulse rectifiers are designed with one delta and one star connected transformers, so the unit itself behaves as two redundant rectifiers by its nature as demonstrated in graphs.
On LCD panel all measurement values, real time base events and failures can be viewed and communicate remotely with RS485 port. All operations are controlled and processed by micro controllers. Adjustable timer is used for boost charging the batteries automatically. Output current, battery current, boost and Float Charge Voltages are adjustable on the user-friendly control panel. Also automatic boost charge can be selected on menu. The automatic boost menu has the options for selecting the boost and float current according to battery capacity.
For dual operations boost inhibit facility is also provided. Boost Inhibit Function is necessarily employed when two DC Chargers with two battery groups operate in a parallel redundant mode. In parallel operation, if two rectifiers start boost-charging at the same time there is danger the DC load would be damaged by overvoltage. So, the principle idea of Inhibit facility is to block any one of the two chargers feeding the load in Boost mode when the other rectifier is charging the batteries in Boost mode; so the system prevents applying overvoltage to the load. This function is primarily handled by a powerful communication between two rectifiers and the use of contactors.

The input and output of the charger are protected against improper use and line disturbances electronically. Input and output can be switched by circuit breakers individually. It has self-protection against over temperature. The alarm contacts can be used for external system in the case of any anomaly. The output is fully isolated from the AC line input.

DC Ripple < 1%
Input and output are protected with MCBs and all settings including boost charge, floating charge and battery charge current can be adjusted via front panel digitally. DC output is filtered by L/C, so DC ripple at full load always lower than 1% to increase battery life.

Battery Charging Characteristics

Ideal and safe charging of batteries is sustained by setting boost and float charge currents. In this way unnecessary boost conditions and deformation of batteries at changing load currents are prevented. Ideal output characteristic via fast microprocessor control.

Soft Start Feature

No inrush current at start up

In sudden load changes dynamic response is 300 msec without overshoot or undershoot to secure the load

AC Ripple at full load < 1%
Battery life is extended significantly via low ripple voltage due to low heat

With this capability rectifier can be used as a power supply even without battery safely with DC Loads

Fully microprocessor controlled rectifier
Thyristor angle is adjusted with load change
½ Load: Phase angle shortened
Full Load: Phase angle at max


Inverter Block

Inverter Communication Interface
The inverter converts DC voltage into pure sinusoidal AC voltage with constant amplitude and stable frequency. The unit works with an IGBT inverter bridge with PWM (pulse width modulation) having high efficiency in the partial load range as well as achieving a low distortion factor at non linear load. Inverter output encompasses 6 IGBT modules, boosting the instant power capacity of the UPS by double fold with comparison to regular systems. This feature allows the UPS to handle higher capacity loads (inrush currents) with smaller capacity devices. In addition, switching at high frequency - 20 KHz. – keeps the output sin wave (THD) undistorted providing reliable solutions for nonlinear loads. On LCD panel all measurement values, real time base events and failures can be viewed and communicate remotely with RS485 port. In the event of mains interruption or failure, the battery connected to the DC input feeds the load automatically and without interruption. If the battery discharge limit is exceeded, the inverter automatically turns off and a warning is given shortly before the discharged voltage limit is reached. Automatic change-over of the load to the bypass mains or a suitable spare supply occurs if the supply from the inverter falls outside the preset tolerances.
Warning Leds

  • Inverter Failure
  • Inverter Output High / Low
  • Inverter DC Voltage High
  • Inverter Overtemperature
  • Inverter not Synchronized
  • Bypass out of Limit
  • Low Battery / Low DC Input
  • Inverter Overload
  • Internal Overtemperature / Fan
  • Failure
  • Bypass MCB OFF
  • Output MCB OFF
  • IGBT SCR Fuse Failure
  • Maintenance Bypass On
  • Backfeed Protection Failure
Set Menu

  • Cold Start ON / OFF
  • Automatic Start ON / OFF
  • ECO Mode ON / OFF
  • Automatic Retransfer Bypass Inhibit
  • DC Cut off Low Battery Level
  • Output Adjustment
  • Bypass Voltage Tolerance Adjustment
  • Synchronization Frequency Adjustment
  • DC Cut off High Voltage Level
UPS Control

  • Remote ON / OFF
  • Rectifier Generator Mode
  • LVD Protection
Alarm Contacts (1 Open 1 Closed)

  • Inverter Failure
  • Inverter Overtemperature
  • Inverter Overload
  • Load on Bypass / Inverter
  • Bypass out of Limit
  • Inverter not Synchronized
  • Low Battery / Low DC Input
  • High DC Input
Dynamic Response

Output at 0-100% load change

Output at 100% - 0 load change
In sudden load changes dynamic response recovery time is 5 msec and max. voltage change is 5%
Swiching wave form

Swiching at 20 kHz
  • There is no waveform distortion for reactive and nonlinear loads
  • Low audible noise
Perfect output waveform with linear loads

Line voltage

Output waveform
Perfect output waveform with non-linear loads

Line voltage

Output waveform
Static Transfer Switch Block
Perfect output waveform with non-linear loads

Source 1 is off limits

Transfer from Source 1 to Source 2 at the peak value of the line with forced commutation

Blackout on Source 1 at peak (Worst case scnario)
Perfect synchronized transfer to Sorce 2 at 2 msec
The microprocessor-controlled static transfer switch constantly monitors the sources connected to the inputs; checks whether they remain within the current and frequency limits and decides if they are synchronized with each other. If the prioritized source is within the determined limits, critical load is transferred over to the prioritized source. If the prioritized source is not within the determined limits, load is then transferred to the 2nd source which is within the determined limits. When the prioritized source reverts to the determined limits, load is transferred back to it. Source priority can be set via front panel. For synchronization-controlled transfers, the static transfer switch transfers the critical load between sources without interruption. In case of an interruption in the source that feed the critical load, critical load is transferred to the other source within less than 5 ms. If sources are asynchronous to each other and asynchronous transfer is allowed, load is transferred to the other source within less than 11 seconds. If asynchronous transfer is not allowed, asynchronous transfer will not take place. Asynchronous transfer can be enabled via front panel.
Thanks to the 3rd source input on the static transfer switch, a 3rd source or line power can be connected to the system. If a 3rd source is to be used, it can be utilized as the last priority. The 3rd source can also be used as a redundant source input instead of failed lines. This ensures reliability through redundant operation. When static transfer switches are to be used as parallel redundant uninterruptable power sources (UPS), the 3rd source input becomes important because in normal operations, both UPSs first transfer the critical load to the line, namely the bypass lines, in case one of them fails and then the UPS in good condition takes over the load. Even though this happens within a short period of time, the risk of interruption or fluctuation will be present for the line. For static transfer switches with a 3rd source input, the critical load is transferred to the line only if both UPSs fail.
Since the static transfer switches have 3 inputs, the 3rd source input functions as the common bypass line of the UPS's when parallel redundant UPSs are employed. This ensures true parallel redundant operation without utilizing bypass from UPSs. Also if the critical load exceeds 100% on the static transfer switches, the load is uninterruptedly transferred to the 3rd source thus preventing unnecessary shutdown or interruption.
Static transfer switches are capable of detecting thyristor failure and transfer the load to a convenient source thanks to the microprocessor control. It indicates a failure warning and shows the failed thyristor module block on the front panel. If the failure of this source's thyristor block can not be eliminated, the load is not transferred to this source again.


Voltage Stabilizer and Isolation Transformer at Bypass


Reliable and uninterrupted switching is secured as tap changing occurs at zero current and at voltage peak level during regulation (shown on the diagram). Thanks to this feature, the occurrence of short circuit at switching instant is prevented.

Since Servo Motor is set in motion with PWM technique, Servo Regulator responds to voltage spikes at optimum pulses to prevent overshoot & undershoot type corrections. As a result, the load is safer against voltage surges and short circuit current. In addition optimum corrections extend the life of the variable transformer and the regulator itself.
In-house developed Servo & Static Type regulators stabilize the mains changes ideally when the Industrial UPS system is on bypass mode. It is particularly employed when differences exist at input and output voltage in the bypass mains. In this case, the bypass transformer adjusts the input to the output voltage; the stabilizer offsets the input mains variations and keeps the output voltage stable; so the voltage between the phases and voltage varieties are stabilized by these safe systems. Since the output voltage tolerance is low (±1 %) for Servo Type Stabilizers, it is an ideal solution for protecting loads when the UPS is on Bypass Mode. However places where the mains changes frequently (20-50 VAC), the mechanical fault possibility increases as the mechanical servo needs to move frequently to compensate the input voltage variations. In addition, the regulation speed may not be enough to stabilize line input. In such cases Static Stabilizer may be a better solution which has no mechanical failure risk because static stabilizers don't include any moveable parts. Also for static stabilizers the speed of regulation is higher than servo stabilizers (500 V/sec) so the response of the system is better for instant mains changes. However output voltage tolerance (± 2 %) is worse than servo stabilizers.

Normal Operation
The rectifier with input isolation transformer converts normal input AC power info DC for the inverter and DC loads and for charging the battery group. The inverter is synchronized with the mains providing it is within the tolerances permitted by the logic, the inverter delivers its closely regulated frequency and voltage with output isolation transformer through the static switch to the load. Where the reference frequency and voltage are outside the permitted limits, the inverter will 'uncouple 'from the mains and will free run using its internal oscillator to assure the high stability power for the load.
Loss of Input Power
In the event of input power failure, the inverter will free run using its internal oscillator and DC loads will operate from the battery until the low DC threshold is reached or the input power to the rectifier is restored. When the input AC power to the rectifier is restored, the rectifier resumes the provision of DC for the inverter, DC load and it will simultaneously recharge the battery. The critical AC load connected to the inverter and the critical DC load connected to the rectifier will not be disturbed during the loss and restoration of the input AC power feeding the rectifier.
Bypass Operation
The inverter is provided with a sensing circuit which can delete transient overload, sustained overloads and short circuits. The sensing circuit initiates 'current limit', which causes the static switch to transfer the critical load to the bypass line without interruption for load security. There is also an isolation transformer with automatic line stabilizer. So, bypass line is also reliable source for the AC load across line fluctuations and disturbances.