Numerical Overcurrent Protection MIT-103

Applications
• Distribution feeders
• Transmission lines
• AC machines
• Capacitor banks
• Transformers

Features :-
Protection
• Phase and ground overcurrent with/without highset (50P, N/51P, N)
• Numerical, true RMS measurement
• 6 characteristics

MIT has three pole version with two phase & one earth element and four pole version with 3 phase and one earth element. MIT is housed in a compact 2/3V drawout vedette case. Settings can be done by a readable Human Machine Interface which also serves for fault indication.

The MIT 103/104/113/114 Protection unit consists of the
following modules within it’s compact dimensions.
• Input Module
• Power Supply and Output Relay module
• Measuring Module
• Front Fascia
The three modules viz. Input, Power supply and Measuring modules are plugged into the Front fascia which houses switches, LEDs and LED display for the human machine interface. All PCBs are well protected from one another and from external environment with best shielding for better electromagnetic compatibility and housed in the enclosed chassis, which is with drawable from the outer case. The drawout case is provided with the required CT shorting contacts. The relay has 3 or 4 input current transformers.The output from the current transformer is transformed to an equivalent voltage and sampled at the rate of 16 samples per cycle and digitized by means of analog to digital converter. The digitized signals are processed numerically by means of microcontroller to effectively remove the DC components and
to drive the Root Mean Square (RMS) value of the input signal. Based on this and the settings, decisions are taken to either elapse the time for inverse characteristics or definite time to operate the trip output relay. Where highset is included (which can be set OFF) an instantaneous tripping is effected once the current exceeds the set value.