Bassmangsj
Member
I design electrical systems to be used with welding robots. The problem I am having is with the ocpd supplied with the robot. The robot itself requires 208-3 phase. On the robot panel is a 30 amp 3-pole breaker that is supplied by robot manufacturer. If the robot is to be installed in a facility that does not have 208 vac I install a transformer with the robot.
The robot manufacturer says to install the transformer downstream of the 30amp breaker. Then 208 vac will be sent directly to the robot controller using a "plug" that fits the high power unit of the robot, so I can not go through another fuse or cb.
I have 3 transformers I can use based on the size of the robot. All are 480/240 delta to 208 wye, 18kva, 10kva, or 4 kva.
Am I wrong to assume the 30amp breaker is too large for the primary of this transformer when I can not protect the secondary because of the "plug" required for the high power unit of the robot?
I figure the primary of the 4kva at 480v should at 6amps (125% of 4.8A), the 10kva at 15amps, the 18kva at 30amps.
Thanks in advance for any advice.
The robot manufacturer says to install the transformer downstream of the 30amp breaker. Then 208 vac will be sent directly to the robot controller using a "plug" that fits the high power unit of the robot, so I can not go through another fuse or cb.
I have 3 transformers I can use based on the size of the robot. All are 480/240 delta to 208 wye, 18kva, 10kva, or 4 kva.
Am I wrong to assume the 30amp breaker is too large for the primary of this transformer when I can not protect the secondary because of the "plug" required for the high power unit of the robot?
I figure the primary of the 4kva at 480v should at 6amps (125% of 4.8A), the 10kva at 15amps, the 18kva at 30amps.
Thanks in advance for any advice.