  The PIP-II Injector Test 1 PIP2IT facility accelerator was assembled in
multiple stages in 2014 $-$ 2021 to test concepts and components of the future
PIPII linac that is being constructed at Fermilab. In its final configuration,
PIP2IT accelerated a 0.55 ms x 20 Hz x 2 mA H$-$ beam to 16 MeV. To protect
elements of the beam line, a Machine Protection System MPS was implemented and
commissioned. The beam was interrupted faster than 10$\mu$s when excessive beam
loss was detected. The paper describes the MPS architecture, methods of the
loss detection, procedure of the beam interruption, and operational experience
at PIP2IT.
