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Power PMAC’s amplifier over current protection has some differences from Turbo PMAC. The first difference is that as long as a motor is activated (Motor[].ServoCtrl>0) and the over current protection is activated (Motor[].I2tSet > 0 and Motor[]I2tTrip > 0) the protection calculations are active. This is true regardless of whether the motor is “Enabled” or “Killed” and is designed for added protection of the motor and amplifier hardware against faulty wiring and bad parameter settings. Another difference is that protection has been added to prevent rapid re-enabling of motors that trip due to over current conditions. This allows proper cooling time for the motor and amplifier that has been overheated due to excessive current. Because of these features there are a few scenarios that can seem like a problem but just need to be understood to be handled properly. One example is that during motor configuration of a direct PWM system it is likely that the Gate1[].AdcStrobe is set incorrectly. This can cause the reading on the ADC to appear as a saturated value of +/-16384 to Ppmac (can be monitored in Motor[].IaMeas and Motor[].IbMeas). When this happens the structure Motor[].I2tSum will quickly count up and become very large. When the proper value is written to Gate1[].AdcStrobe then the measured ADC is no longer saturated and Motor[].I2tSum will start counting down toward 0. But until Motor[].I2tSum is less than Motor[].I2tTrip the motor will not be allowed to enable. Other similar scenarios exist and what they all have in common is that Motor[].I2tSum has counted to a very large number and must unwind before Ppmac allows the motor to be enabled. To recover from these situations you must wait until Motor[].I2tSum unwinds. To speed up this process you can temporarily set Motor[].I2tSet = 0 which will force Motor[].I2tSum = 0. If you do this make sure you restore Motor[].I2tSet to its proper value otherwise you will no longer have protection. This situation should never be encountered during normal operation since all parameters will already have been configured. It can be encountered during a setup session where several seconds can pass between manually entering the ADC strobe word and activating the motor and I2T protection. It can also be encountered at power-on if your PWM drives send out full-scale ADC readings for any significant time period while they are powered up.
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