Final answer:
The terminal t1 connects to the power supply, t2 connects to the control circuit, and t3 connects to the load circuit on a contactor or motor starter. There is no direct grounding circuit connection on a contactor or motor starter, but a grounding circuit may be connected to the case of the appliance or equipment.
Step-by-step explanation:
The terminal connections of a contactor or motor starter are used for various circuits. The terminal t1 connects to the power supply, providing voltage and current to operate the device. Terminal t2 connects to the control circuit, which is responsible for activating or deactivating the contactor or motor starter. Terminal t3 connects to the load circuit, which includes the appliance or equipment being controlled. Finally, there is no direct grounding circuit connection on a contactor or motor starter; however, a grounding circuit may be connected to the case of the appliance or equipment.