Although your question has been answered, it appears maybe you didn't catch it, so I'll reiterate it and try to clear up some other issues for you.
Yes, it is permissible to "over size" a breaker on a MOTOR branch circuit, IF you have an Over Load Relay in the circuit as well.
In a factory built "combination starter", that will often mean the circuit breaker will be a "mag-only" type, commonly called an "MCP", but technically, that was a trade name for a long time so most other mfrs used other terms. Officially in the NEC it is referred to as an "Instantaneous Trip" (IT) circuit breaker. BUT, you cannot use those in the field, they are ONLY allowed to be used in a factory built and UL listed combination starter as part of a specific series string with the other components. So in your skid, if they built it themselves (which from the fact that they used a residential plug-on breaker is a 100% certainty), they would NOT have been able to use an MCP. That explains the Thermal-Mag breaker. I happen to think that is an EXTREMELY poor choice of breaker, read on.
The Siemens QP is a residential breaker, NOT really intended for industrial use and absolutely not suited for what they are using it for. Residential breakers are built and tested to somewhat "loose" tolerances for instantaneous trip values. If you were to find (and it's not easy) a "Time Current Curve" (TCC) for that breaker, it would indicate that the magnetic trip is designed for 10x the breaker rating, so in this case 600A. In reality, that breaker will not EXCEED 10x the rating, but is acceptable to be sold even if it trips at 4x the rating, so 240A. That's a much wider tolerance than anyone would accept for an industrial duty product, where nuisance tripping can have very substantial consequences in lost production and therefore revenue. In a residence, the chances of starting a large motor like that are almost nil and the consequence is just an angry homeowner who maybe has to go find the flashlight.
You are allowed to go to 250% of the motor table FLA of 59.4A for a 208V system, so the breaker can be as high as 150A if necessary (next size up). If you decide to change it to make this problem go away, I suggest finding a thermal-mag breaker with a 150A frame, that has an ADJUSTABLE magnetic trip dial on it, just like on the MCPs (it would be the exact same trip unit). The mag trip unit will go up to 1500A that way. I would set it for 700A at first, see if that holds. This is roughly the limit of what the NEC allows (1300%), but there is an exception IF you can show that this does NOT hold in; if not, then you are allowed to go to 1700%, so roughly 1000A. I would not go there first however. Start off with as low as will hold in. Since 1000A is going to be the upper limit for you anyway, you could go with a 100A T-M breaker, it's mag trip will go to 1000A and it will be a little less expensive.
I also think your OL relay is too high. With a nameplate FLA of 48A at 230V you MIGHT be able to get away with using 53A (more later). MANY OL relays will have ALREADY factored in the "pick-up point" allowable per the NEC of 125%, so you do NOT add another 25% on top of that value, you set it / select it for the ACTUAL value. But at 75A, you are even above THAT value! Most likely they were using the 140% allowance for a 1.15SF rated motor and used the NEC tables for it at 230V, meaning 54A. 54A x 1.4 = 75.6A, that makes sense to that setting. But, that is not what you HAVE. You have a 1.15SF motor rated at 48A, so the absolute maximum it can be set is 67.2A.
Now lets get into the voltage rating. At 10HP and below, there is a general (but not official) understanding among motor mfrs that these smaller motors can easily tolerate being run at 208V as long as there is not too much voltage drop. But at 20HP, all bets are off. So unless you contact the motor mfr and ask them SPECIFICALLY if it is safe to run this motor on a 208V system, you cannot assume that. Yes, 208V is within the -10% of 230V, but if the 208V drops to 197.6V as the utility is allowed to do (-5%), now the motor terminal voltage is not within tolerance and you could lose the motor. That said, that's one of the "fudge factors" behind using a motor with a Service Factor of 1.15; it allows for some unexpected voltage drop and the current increase that entails. So the point is, even if you want to chance it by running it at 208V, you MUST get the OL relay set at a lower value to protect that motor. Personally, I would set it below 67.2A, likely at around 60A, but that's just me.
