Safety relay circuit for large power contactors

An apparatus for monitoring a first main contact within a first contactor, wherein the first contactor further includes a first auxiliary contact and a first primary coil, wherein energizing of the first primary coil by way of a power source causes each of the first main contact and the first auxiliary contact to switch, the apparatus comprising:

• a trigger coupled to a power terminal capable of being coupled to the power source;
• a first circuit that is electrically connected to the power terminal upon actuation of the trigger and that has an on state and an off state,
• wherein the first circuit switches from the off state to the on state when the power source is electrically connected to the first circuit by way of the power terminal if an additional signal is received by the first circuit at that time,
• wherein the first circuit remains in the on state once it has entered that state until the power source is disconnected from the first circuit, and
• wherein the first circuit causes the primary coil to be energized when the first circuit is in the on state;
• a second circuit coupled to the first circuit and to the auxiliary contact, wherein the second circuit prevents the additional signal from being received by the first circuit when the auxiliary contact is in a first position;
• a third circuit that causes the first circuit to be electrically disconnected from the power terminal when the third circuit is in a first state, and further causes the first circuit to be electrically connected to the power terminal while the third circuit is in a second state;
• a fourth circuit coupled to the third circuit and including portions of the first and second circuits, wherein the fourth circuit causes the third circuit to enter the first state when at least one of:
• the first circuit enters the off state such that the primary coil becomes and remains deenergized for a first period of time, and
• the first auxiliary contact remains in a second position for the first period of time while the first circuit is in the on state.