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Ques

What is UPS?

Ans.

UPS- Uninterruptible Power Supply System is equipment connected in between the mains supply and the critical loads (IT / Electronic / Industrial-Electrical equipments) to provide Uninterruptible, Clean and Clear Power.

   

Ques

What are the Types of UPS available in the market?

Ans.

Primarily there are three types of UPS systems based on the technologies used in them. They are OFFLINE (Stand-by), LINE INTERACTIVE & ONLINE UPS SYTEM. Of late two more technologies (Delta Conversion, Rotary / Dynamic (Flywheel technology) are also available in the market.

   

Ques

What is an OFFLINE (Stand-by) UPS SYSTEM?

Ans.

In OFFLINE UPS systems the output load is directly connected to the input mains (utility) supply without any correction in between. Sometimes the Input voltage is filtered with voltage buck-boost arrangement to remain within a specified window. In case of any major abnormality at the mains supply including power failure, the load is transferred to the inverter (supplied from battery) within few milli-secs. Output from the OFFLINE (Stand-by) UPS systems are generally Square wave or Modified sine (Quasi-sine) wave during back-up mode.

   

Ques

What is an LINEINTERACTIVE UPS SYSTEM?

Ans.

LINE INTERACTIVE UPS systems are upgraded version of OFFLINE UPS Systems only. These are microprocessor controlled UPS systems, which always monitors the Input Mains (Utility) supply and reacts to any variations. The transfer time in these type of UPS systems are much less compared to OFFLINE UPS systems. A true Line Interactive UPS system employs Bi-directional converter in stead of separate Charger and Inverter modules and the output waveform during back-up (battery) mode is pure sine wave.

   

Ques

What is an ONLINE UPS SYSTEM?

Ans.

In ONLINE UPS systems, the inverter always feeds the output load. The input AC from the mains (Utility) supply is converted to DC, which charges the Battery Bank & also drives the INVERTER. The input DC to the Inverter is then converted back to AC to feed the output load. The Output AC, thus available from these UPS systems are very clean and free from all possible power problems due to the two stages of conversions in the process. True online UPS systems are also called “Double Conversion UPS” and used for all critical and hypercritical applications and in higher loads (>10 kVA).

   

Ques

What is the difference between "KVA rating" and "KW rating" of UPS?

Ans.

“KVA” denotes apparent power; whereas “KW” is for active power. Mathematically KW= KVA*PF, where Power Factor (PF) is the cosine of the phase angle between the voltage and current for linear loads.

   

Ques

What is the Input Power Factor (p.f.) of the UPS at different loads?

Ans.

Input Power Factor of an UPS is independent of the type of load connected to the UPS for true ONLINE (double conversion technology) UPS systems. However, Input Power Factor of the UPS improves with variation of output load percentage of 0-100%. Input Power factor is also lower at higher input voltage and goes on improving as voltage reduces.

   

Ques

How much is the static switch transfer time in Asynchronous and Synchronous mode if inverter fails?

Ans.

During synchronous mode the Inverter is in phase with the Mains (Utility) Supply and frequency locked with the Bypass, hence the transfer time is 2-4 ms. In case of Asynchronous mode the transfer time is 15-20 ms.

   

Ques

How to derive the required capacity of UPS for a given load?

Ans.

The total KVA is equal to the sum of the connected loads’ power requirements in kVA including the inrush power consumption (normally during ‘switching on’ of the equipments), i.e. Steady State KVA + Inrush KVA. The required UPS capacity in KVA should be (at least) 20% more than the total load (Steady State + Inrush) derived as above.

   

Ques

What is the THD (total harmonic distortion) of the UPS and how it is measured?

Ans.

Total Harmonic Distortion is the distortion of waveforms due to the presence of harmonics, which changes the AC waveform. These harmonics are generated mostly due to inductive loads. The THD is generally denoted in %. Total Harmonic Distortion is measured using Distortion meter. For linear load it is less than 1% (typical) and less than 2% (maximum). For nonlinear load with crest factor 3:1 it is less than 5%.

   

Ques

What are the types of load applied to UPS during testing?

Ans.

Resistive load and non linear load for normal testing and Inductive load on special request.

   

Ques

What happens if UPS fans fail?

Ans.

Fans are provided for cooling of wire wound components as well as heat sink on the electronic components of the UPS. For any failure of cooling fans, the internal temperature of the UPS systems increases and if the problem persists beyond certain duration, the inverter trips on “OVER TEMEPRATURE” mode to protect the electronics of the UPS.

   

Ques

Is UPS output isolated from its input for all types of UPS systems?

Ans.

Incase of OFFLINE & LINE INTERACTIVE, the output is not isolated from input. In case of ONLINE UPS systems the input and output is electronically isolated.

   

Ques

What type of UPS systems REEM Batteries & Power Appliances Co. SAOC offers?

Ans.

REEM Batteries & Power Appliances Co. SAOC offers Offline (Stand-by) / Line Interactive and True Online (Double conversion technology) UPS systems.

   

Ques

Why there is no alarm or indication for any fan failure?

Ans.

During fan failure, the temperature of the Heat Sinks and with wire wound components of the UPS systems increases and if the problem persists for a longer period the UPS trips on “OVER TEMPERTAURE”. Thus fan failure is indirectly indicated by “OVER TEMPERATURE” itself.

   

Ques

How do I monitor UPS from some remote location in the Network?

Ans.

Latest state-of-the-art UPS systems like “REEM UPS” can be connected to a network through SNMP agent / Manager (Hardware). By loading SNMP software on any one of the workstations in your network for initial l configuration and subsequently to receive traps from UPS or by installing SNMP manager on NMS, the UPS can be monitored from remote location over a network. This can be extended through Internet also by designating a specific TCP/IP address of the UPS and the UPS can thus be monitored over Web from anywhere in the world.

   

Ques

Do you offer shutdown of multiple workstations?

Ans.

Yes, REEM UPS systems offer shutdown of multiple workstations. The same can be done through Multiport and Using our WEBPOWER software.

   

Ques

Does one need to install any client software to monitor the UPS parameters while using SNMP card for Web Monitoring?

Ans.

No, only web Browser is required

   

Ques

Do REEM offer shutdown software for Windows / Linux?

Ans.

Yes, REEM UPS systems provide auto shutdown software compatible for Windows / Linux etc.

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