We are using rectifier modules the load current in 63 A and the float voltage is 54.5 V. We are using 6 modules each has maximum dc output of 28.1 A. If 2 modules go faulty are 4 modules enough ?? Just to keep in mind that more than 80% efficiency cannot be used for modules.

Sameer, Since you have told us nothing about these modules except their efficiency (without defining it), how they are connected or the load, you can see that the output can be 4x28.4=113.2Amps, or 2x28.4=56.8A knowing what you know then you should be able to decide.

Alan

I got that. Actually these are Eltek Flatpack 1500 48V DC rectifiers. We are using for telecom purposes. These are designed for 24KW power system. The problem is that in various sites these modules go faulty and sometimes we dont have new modules to replace the faulty one. So i just needed to know if load current is already provided and we have an idea that how much load single rectifier module is giving can we calculate the efficiency of these modules ?? These modules are also charging 155 AH battery bank 12V for backup. 4 batteries in one bank i.e 12x4V=48V.

Sameer, According to the manufacturer's datasheets those units have a MTBF (Mean Time Between Failure) over 350,000 hours, therefore it seems odd that you should have so many early life failures. I would be talking to the manufacturer about that to see if they can help you pinpoint the problem.

As far as efficiency, they are listed as 94% efficient with an option for 96.5%, certainly you can verify this by accurately measuring the output power and dividing by the input power.

It also list NiCd as the battery chemistry when used as a charger. It's best if you contact the manufacturer directly so that they can verify the overload capability.

Alan

Thanks alot Alan