Highly Reliable UPS

Pdf files

1. What is the difference between "KVA rating" and "KW rating" of UPS?
Ans. The equation is kW= kVA *pf. In general kW is active or useful power and kVA is the vector sum of active power and reactive power. The equation is kW= kVA *pf.

 2. What is the Input Power Factor (p.f.) of the UPS at different loads?
Ans. Power factor is a function of phase displacement angle between voltage and current and distortion factor. It is calculated as a ratio of real power to apparent Power drawn by load. PF is low at lower loads and goes on improving at higher loads. PF is also lower at higher input voltage and goes on improving as voltage reduces. Input Power Factor is independent of type of load for double conversion technology.

For nonlinear loads the power factor is low due to the presence of high percentage of harmonics present in the load current.

 3. How much is the static switch transfer time (Break in output) in Asynchronous and Synchronous mode if inverter fails?
Ans. In synchronous mode this break is less than 5 mS because of Static Switch in output and Inverter is phase and frequency locked with Bypass.
In case of Asynchronous mode it is between 15-20 mS.

 4. What is the maximum rating of the UPS offered by ENP ?
Ans. 400kVA Single module capacity. Six such modules can be paralleled for expansion up to 2400 kVA or for redundancy

 5. How to arrive at correct UPS capacity for a given load?
Ans. Estimate steady state ( normal running ) kVA of the total load. Determine inrush kVA of the largest load in the total load distribution. The rated kVA capacity of the UPS should be 85% of the sum of above two [Steady state kVA + Inrush kVA].

This is under the assumption that all loads are not switched on at the same instant and largest load is started while all remaining loads are running

 6. What is the % total harmonic distortion (%THD) of the UPS output voltage and how it is measured?
Ans. 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%.

 7. What is the overload capacity of the UPS?
Ans. 110% for 60 minutes 125% 10 minutes 150% 60 seconds
Maximum fault current under short circuit will be less than 200% of rated current.

 8. What is the type of load applied to UPS during testing?
Ans. Resistive load and non linear load for normal testing and Inductive load on special request of inspection authority

9. What happens if UPS fans fail?
Ans. Fans are provided for cooling of wound components as well as cooling of heat sinks. If these fans fail internal temperature of the unit will increase and at heat sink temperature of 850 C it will give indication of 'Over Temperature'. If this persists then Inverter will be switched off after 2.5 Minutes

 10. What is the degree of protection (IP protection) applicable for ENP UPS?
Ans. IP 20 even with front door open. IP 31 on special request.

 11. Is UPS output isolated from its input?
Ans. Yes, double wound isolation transformer of full load UPS rating is used at inverter output, which ensures complete isolation from input.

 12. Can the UPS output neutral be earthed?
Ans. Yes, provided bypass isolation transformer is used or the operation of static switch is permanently disabled.

 13. What type of UPS ENPIL is manufacturing?
Ans. On line UPS and line interactive UPS systems

 14. What is burn in test? How much duration the heat run of standard UPS is carried out ?
Ans. Burn in test means UPS kept in running condition at some load or at no load. (Burn in) test at full load and for minimum 8 hours is carried out on every UPS

 15. Why there is no alarm or indication for any fan failure?
Ans. Fan failure is not directly indicated because on failure of fan heat sink temperature of UPS will increase and this rise is depends upon percentage of load on UPS. Fan failure indirectly indicated as 'Over temperature'.

 16. Does ML 3.0 send traps to SNML1.5 client?
Ans. Yes, ML 3.0 can be used to send traps to existing ML1.5 clients. What you need is network shutdown license for those many clients where you want to send traps.

 17. How Netcom can be used to send trap to Workstations in the network?
Ans. Netcom provides you an option to send traps to twenty workstations in your network. One of which could be your NMS

 18. How do I monitor UGXT UPS from some remote location in the Network?
Ans. Hookup UPS to network via our SNMP agent called Intellislot, Load either ML1.5 or ML3.0 on one of workstation in your network to receive traps from UPS or install SNMP manager on NMS.

 19. I am using UPS model as PSP and is interested in auto shutdown of workstations, how to go about the same?
Ans. PSP UPS can also be used to provide auto shutdown facility

20. Do you offer shutdown of multiple workstations
Ans. Yes

21. What is the difference between the software SiteNet1 and Multilink auto shutdown software's?
Ans. SiteNet1 is primarily used for standalone configuration while MultiLink is used for Network configuration based on SNMP protocols

22. What is the difference between the multi port and multi Link?
Ans. Multiport is a device used to hookup more than one workstation to one UPS, while MultiLink is a software used to carry out auto shutdown of one or multiple workstations using Network Shutdown license

 23. Do I need to install any client software (Package) to monitor the UPS parameters while using Netcom?
Ans. No , only web Browser is required

 24. Can I send a message on pager about the status of UPS automatically on any event that occurs on the UPS?
Ans. Yes, the option is available in Sitenet1 , SiteNet2 and ML3.0 s/w

 25. Can I run any scripts on certain events before the shutdown of the OS?
Ans. Yes, SiteNet1 , SiteNet 2 and ML3.0 as well as ML 1.5 prompts you an option to run any script before OS shutdown.

 26. Do you offer shutdown software for linux operating system?
Ans. Yes, MultiLink 1.5 and MultiLink 3.0 softwares are compatible with following Linux for Intel, 2.2-2.4 Kernel: Red Hat Linux 7.0,7.1 Caldera Systems,Inc. OpenLinux 2.4,3.1 SuSE Linux 7.1,7.2

 27. Do you offer shutdown software for windows 2000?
Ans. ML3.0 and ML1.5 software's provides auto shutdown for windows 2000.

 28. How to monitor S7400M UPS in network?
Ans. Netcom can be used to monitor S7400M UPS in network

 29. Why do ENPI PEC systems use Electric reheaters?
Ans. When temperature conditions are achieved and Relative humidity (RH) has to be achieved, the A/c system goes on to a dehumidification cycle. During de humidification cycle (De-hum) if any of the electronic equipment is switched OFF or dehumidification cycle is called for at night, when the load on the A/c is partial, along with dehumidification there will be a drop in temperature. Since temperature is to be controlled within ± 1°C and RH is dependent on temperature, the heater will come ON to compensate for the sensible heat loss in the room so that the temperature is maintained during dehumidification cycle. Therefore ENPI A/c used heaters only for Sensible Heat Compensation. ENPI used Electric reheat for sensible heat compensation only. The heater will come ON only if the load goes down to 30% of the design load i.e. of the load in the Telephone exchange goes below 9.0 TR where 30TR working + 10TR standby

system is installed. This situation will never occur in places like Mumbai etc. but only possible only where extremely low ambient conditions prevail like in Delhi and Northern part of India. The heaters are of low watt density and highly efficient through Fin tubular design and hence is optimized on energy consumption. Hot gas reheat is an old method of providing heating during dehumidification cycle. ENPI control temperature and RH simultaneously, since they are inter-related (For your information the approximate relationship is 1°C increase will be 3% RH decrease and vice versa approximately as per pyschorometer chart) ENPI microprocessor controller with the PID logic for temperature and Dew point logic for RH have simultaneous control on these two parameters resulting in optimization of power. This is built through an Algorithm in the Microprocessor as follows: RHadj = RHact + 3 (Tact - Tset) All other Microprocessor Controllers available do not have this feature of SIMULTANEOUS control on temperature and humidity but have Sequential control of Temperature and humidity. This means, Temperature is controlled 1st and then RH is controlled. When temperature reaches set point and RH is not achieved, the unit goes on to dehumidification cycle. As a result of dehumidification, the supply air temperature reaches lower temperature and hence requires heating to bring it to normal temperature. Due to this heating the temperature in the room goes higher. This follows a cycle of cooling and heating to achieve the desired level of temperature and RH. When there is a sequential process of control of Temperature and RH, there is excessive power consumed through continuous heating. To optimize on this power, the principle of Hot gas reheat comes into picture. Hot gas reheat feature uses the waste heat from the Compressor that would have otherwise been rejected by the condenser into the atmosphere, to heat the air during the dehumidification cycle. So, this feature is not required in ENPI sort of systems which have a better logic of Microprocessor and has inbuilt power saving features. Hot gas reheat saves power from the additional power being spent and hence is not an optimal process. There are no solutions for the following situations when Hot-gas reheat is used as a feature: 1. Heating as elaborated in the text is to bring back temperature into control band in part load conditions. If in Delhi, during winter, if the ambient temperature drops to 5°C or 10°C and there is part load condition in the exchange, to control the temperature one would require heating process. In this a system, which has Electric reheat, will function in the heat mode and achieve the desired condition. If there is a HG reheat feature, the compressor has to come ON for the HG reheat to operate. This will mean part cooling and part heating. This is a wasteful & slow process not benefiting the user at all. There are no explanations to this question by the firm who have propagated this feature. 2. The HG reheat coil acts as an additional resistance to the air flow and hence adds to the load of the Fan motor resulting in higher power consumption of the Fan motor. 3. The HG reheat coil is placed very close to the Cooling coil in the design of the systems. This results in serious maintenance problems since the inner portion of the HG reheat coil and outer portion of the Evaporator coil beneath the reheat coil can never be cleaned and hence deteriorates the efficiency of the Air-conditioning unit itself. 4. Compressor throws out oil along with refrigerant since both are miscible. If oil accumulates in the copper tubes of the HG Reheat coil, this will result in efficiency drop of the heat transfer resulting in longer time for reheat. Hence HG reheat feature in an air-cooled system with long piping is a dangerous situation. With all the above points in view, we recommend removal of Hot Gas reheat feature, which is not an energy saving feature at all in our opinion. 

30. Please confirm if we can commit 18 deg +/- 1 deg C temperature control and 50 +/-5 RH control with our PAHU with CEMS 100 installed in a switch room. Incase not possible, I would require a technical reasoning also.
Ans. Normally, CHW temperatures are in the range of 7 deg C. This corresponds to 44.6 F of water temperature. There is no way that the ADP can be anything lower than this temperature. ADP shall be around 8 deg C i.e.46.4 F. At 46.4F ADP, the lowest room temperature (assuming SHF of 0.95) that can be achieved is 21 deg C and 50% RH Nothing lower than that. If the entering water temperature is 5.5 deg C, we can go down to 20 deg C, for which you need to take Customer's opinion. Conversely, if you want to achieve 18 deg C, there is a remote possibility, without any control on RH i.e. RH will be more than 75%. Conclusion: Customer should accept 22 deg +/- 1 deg C and 50% +/- 5% RH with EWT of 7 deg C and LWT of 12 deg C. If even competition is claiming otherwise, we can prove to Customer that this is not possible psychometrically.

 31. What are the requirements for the UGXT machine to be monitored on the NMS?
Ans. You would be requiring the SNMP hardware agent Intellislot with the valid Tcp/Ip address and Ethernet port along with the SNMP Manager for specific NMS for more info click below.