The SE-CS10 series current transformers (CTs) are key components of the Littelfuse protection relay product line. Littelfuse SE-134C and SE-135 Ground-Fault Ground-Check Monitors are designed specifically for use with the SE-CS10 CTs. A Littelfuse SE-330 Neutral-Grounding-Resistor Monitor and a Littelfuse SE-701 Ground-Fault Monitor can also be equipped with the SE-CS10 series to achieve the desired ground-fault-trip settings. Littelfuse motor- and feeder-protection relays can also make use of the SE-CS10 series either to measure phase current or ground-fault current.