The MLC Series from LTH Electronics is a miniature plug-in single-circuit conductive level controller for industrial liquids with resistance up to 30 kΩ. Using conductive probe electrodes, it detects liquid presence at a set point and provides relay output for pump start/stop, high-level alarm, or low-level alarm. Variable sensitivity adjustment across High and Low ranges accommodates different liquid conductivities without changing probes.

How does conductive level detection work?

A low AC voltage is applied between the conductive probe and a reference electrode (usually the tank wall or a second probe). When liquid bridges the gap, current flows and the MLC detects the change in resistance. The sensitivity control sets the resistance threshold for triggering — High Mode spans 450 Ω to 48.9 kΩ, Low Mode spans 210 Ω to 45.7 kΩ (values based on a conductivity cell with constant K=1.0). For low-conductivity liquids, a K=0.1 cell shifts the effective resistance range upward by a factor of 10. This method suits water, wastewater, and mildly conductive process fluids — it is not suitable for non-conductive liquids such as pure oils or deionized water.

What mounting and probe options are available?

The MLC controller plugs into a KF11 surface-mounting socket (part 114/003). Electrode options include a 0.25-inch 316 stainless steel rod (part 1650) and a stainless rod with plastic sheath and graphite tip (part 1651) for chemically aggressive environments. Both electrodes use E7 series polypropylene holders; the E7P variant withstands process pressures up to 20 bar. Mounting brackets B1 through B4 support one to four E7 holders respectively. IP 65 enclosed versions house single or dual MLC controllers for surface mounting in wet or dusty environments.