Releases in Circuit Breaker

Yes, Guv. Anybody can do this because the ratings are on a permanently-attached label on the front of the breaker.

http://lmgtfy.com/?q=what+are+the+releases+in+MCCB+circuit+breaker

No Need to put Circuit Breaker after MCCB (Moulded Case Circuit Breaker)
[1] Over Current Release for O/L & Short Circuit Protection
It May be Thermo-Magnetic or Microprocessor based as well.uP based will/may offer Earth Fault Protection also.
[2] Shut Release (or Trip Coil) for Electrically Tripping the MCCB
[3] Under Voltage Release for No Volt Protection

Thermal-Magnetic:

Over-current (Time-delayed) & Short-Circuit (Instantaneous)

with optional add-on external earth fault release

Micro-processor based:

Over-current with time delay (long-time pick-up & time delay)

Short-circuit with time delay (short-time pick-up & time delay) with limits on current setting & on time setting (limited by the short time withstand capacity of the MCCB)

Short-circuit Instantaneous (Instantaneous): To over-ride the Short Time Pick-up release, if the fault current is beyond the setting made in this instantaneous release

Ground-fault with time delay (Ground fault Pick-up & time delay)

Ground fault Instantaneous

I2t ON/OFF

Thermal Reflectivity ON/OFF

Thermal Memory ON/OFF

Instantaneous Doubling (Cold load Pick up ON/OFF)

Under voltage Release

Shunt Release

It depends completely on the trip unit that is fitted on the MCCB ... can vary from basic up to the most sophisticated . I advise to check on the existing CB, if this is your case, or to write your need on the spec you issue, if this is your case .