Quote:
Originally Posted by Mk.32
If a CIM is pulling 132amps wouldn't PD 40amp breakers throw? And there is a 120amp breaker, so the robot should never pull more then 120 amps, and if it tires to wouldn't the breaker just kill power?
Those power supplies look like the deal of the decade for high power applications, I might get one to run my battery charging array...
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The breakers are thermal-limited to 40a or 120a.
This does not mean that any current greater than the trip point will instantly trip the breaker.
Current transients can heat the breakers for a short time without tripping them. For the 120a main breaker, this number is several hundred amps for many seconds - I seem to remember 200a for a minute, but I don't have the spec sheet on hand. The 40a breakers can also take several seconds to trip under CIM stall load (which IS ~130a).
All motors will pull their stall current when starting (assuming supply voltage = spec voltage). This is because the current draw is proportional to torque, which is inversely proportional to speed. Since the speed is 0 when starting, torque is stall torque, so current is stall current. As the motor applies a force to the output, the output beings to move and the motor's output torque and input current go down. The motor will still draw ~130a for a short period of time.
Assuming 4 drive CIM's, then a forward/reverse launch would instantaneously draw ~520a.
Server power supplies are not designed for high current transient loads like motors. They are primarily designed for steady-state computing and cooling loads, which do not produce transient current draws anywhere near that of CIM motors. Unless I had data or specs to say otherwise, I would assume the spec output current is the peak output current, and a single power supply would not be able to handle the load of multiple CIM motors starting.