Can I use an external emergency stop system to interrupt the supply to the main contactor coil?
As far as the safety of the drive is concerned (and our warranty) it is crucial that the drive controls the main contactor without any external interference. Any emergency stop system should be connected into the coast stop input, terminal 34. This will allow the drive to safely cease current flow prior to opening the contactor - in about 100 milliseconds.
However, should local safety codes mandate that the contactor coil supply can be interrupted directly by emergency stop thus not relying on the drive control electronics, you must put an auxilliary contact of the contactor in the run input on terminal 31 - at least that way the drive has a reasonable chance of shutting down current flow prior to the bridge supply being discontinued. In addition, there are some sites that insist that all supplies to the drive are interrupted under emergency stop conditions. This of course means that the line to neutral control supply also disappears. This is less of a problem than you might suppose because the digital drive is designed with a power supply that is self supporting for a short while after power off whilst it does certain housekeeping tasks. In effect there is very little difference to the drive if you remove all supplies at the same time as long as you have adhered to the above recommendations concerning the run input.