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The Indian Army is in the process of upgrading T-90 eqpt fleet with environmental control with APU.

Some important questions:

Q.2. Can the main assemblies of APU, heat exchangers and pump etc be placed in the present location of SPTA/assembly box outside the turret with only the cooling units and ducts inside the air compartment to direct cool air at entire crew stations viz driver, gunner and commander and electronic systems/subsystem in the vicinity.
Q.3. Does the system change the silhouette of the tank in vertical and horizontal plane or foul with existing features on the tank?
Q.4. Does the system operate from the mains, 220V AC 24V DC output and also from APU output?
Q.5. Is the system protected from small arms fire and splinters?
Q.6. Is the system rugged enough to withstand the normal hazards of cross country move in plains, semi desert and desert terrain?

Q.12. Does it provide adequate cooling inside the crew compartment for efficient functioning of the electric system / sub systems in the ambient temperatures obtaining in our deserts, semi deserts and plains in all seasons ?
Q.13. Is the ECU capable of operating continuously for minimum 10 hrs without affecting its efficiency?
Q.14. Is the AC easy to retrofit onto a T-90S/SK tank at field workshop level ?



AUXILIARY POWER UNIT (APU)
Q.15. Does the power unit (APU) conform to the following specifications :-
(a) Rating capable of catering to the power requirement of air conditioner designed to maintain a temperature differential of 25º± 5ºC over the ambient
temp range of 30 + 3 0C to 43 0 + 3 0C?
(b) Capable of operating the following system of the tank in silent mode :-
(i) Operation of night vision Devices and TI ESSA ?
(ii) Operation of Day Gunner Sight 1G 46 and LRF ?
(iii) Ballistic computer unit ?
(iv) Operation of Gun Control Equipment including power traverse ?
(v) Operation of Radio Sets including tank intercom ?
(vi) Battery charging ?
(vii) Operation of navigation aid equipment ?
(c) How long can the APU run above systems in silent mode?

Essential Characteristics of Air Conditioner with Auxiliary Power Unit (The System)
Q.16. What is the reliability of the system in term of MTTR and MTBF?
Q.17. Is the system capable of functioning for minimum mean time between overhaul (MTBO) of 1000 hours for APU and ECU?
Q.18. Are the assemblies / components of the system hermetically sealed?
Q.19. Is the system modular in design?
Q.20. Is the APU air cooled / water cooled and diesel driven?
Q.21. Is the APU compatible with concerned assemblies of the T-90 tanks?
Q.22. MTBF of APU should not be less than 5000 hours of operation and MTTR should be 4 hours.
Q.23. Does the APU have an inbuilt overload protection system?