DIAGNOSIS That's an overload. Even though it's on its own outlet, that outlet is almost certainly sharing a 15-amp circuit with other rooms or appliances. The SLPAC10 draws about 9-10 amps at startup, which leaves little headroom.
FIX You need to isolate the circuit. Find which breaker in your panel corresponds to that outlet (by trial and error with a lamp). Once identified, turn ONLY that breaker off and see what else in your house loses power—lights, other outlets, maybe the fridge. If anything else is on that circuit, you've found the problem. The AC needs to be the only major draw on that 15-amp circuit.
IF THAT DIDN'T WORK If it's truly on a dedicated circuit and still trips, the issue could be a weak/old breaker or a problem with the unit's compressor drawing too much current as it heats up. Try plugging the unit into a different, known-strong circuit (like a kitchen outlet) with an extension cord rated for high amps (14 gauge or lower) as a test. If it still trips, the unit may have an internal fault.
HEADS UP Never use an extension cord for permanent use, only for diagnosis. And never plug it into a GFCI outlet (the ones with test/reset buttons) if you can avoid it, as the motor's startup surge can nuisance-trip those too.