Solid State Liquid Level Temperature and Process Controls

Model ELS
Model ELS

  • Solid state amplifier with SCR and control relay
  • Low AC signal voltage
  • Compact printed circuit design
  • 1/4" quick-connect terminals
  • Insensitive to transients
  • Built-in holding circuit for differential levels or manual reset
  • Plug-in dust-tight relay

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Model ELC
Model ELC

  • Compact solid state design
  • Single level forward mode operation
  • Low AC signal voltage
  • Transient-protected circuit, positive on/off design eliminates relay chatter
  • Built-in holding circuit for differential levels or manual reset
  • Limits short circuit probe current to 10MA/24VAC

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Model LCT
Model LCT

  • For standard applications up to 100,000 ohms
  • Built-in delay-on-make
  • Positive on/off design eliminates relay chatter
  • Solid-state amplifier with potentiometer for signal sensitivity adjustment
  • Built-in holding circuit for differential levels or manual reset
  • Limits short circuit probe current to 10MA/24VAC
  • Pre-wired auxiliary contactor available for heavy loads exceeding capacity of plug-in relay
  • Interchangeable with model LCS Liquid Level Controls

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Model LCS/LHS
Model LCS/LHS

  • LCS model for standard applications up to 100,000 ohms
  • LHS model for standard applications up to 3,000,000 ohms
  • Positive on/off design eliminates relay chatter
  • Solid-state amplifier with potentiometer for signal sensitivity adjustment
  • Limits short circuit probe current to 10MA/24VAC
  • Built-in holding circuit for differential levels or manual reset
  • Pre-wired auxiliary contactor available for heavy loads exceeding capacity of plug-in relay
  • Interchangeable with model LCT Liquid Level Controls

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Model LC
Model LC

  • Adjustable sensitivity up to 100,000 ohms
  • Solid-state amplifier with SCR and control relay
  • Limits short circuit probe current to 10MA/24VAC
  • Low power consumption
  • Ideal for longer-than-average probe runs
  • Temperature stabilized from +32o F to +140o F
  • Shielded, grounded isolation transformer
  • Auxiliary contactor available for heavy loads exceeding capacity of plug-in relay

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Model DLC
Model DLC

  • Ideal for pump and heater applications requiring lockout in the event of loss of fluid
  • Limits short circuit probe current to 10MA/24VAC
  • Solid-state amplifier with SCR and control relay
  • Sensitivity to 100,000 ohms
  • Built-in holding circuit for differential levels or manual reset
  • Three-probe circuit eliminates relay chatter
  • Allows for applications requiring manual priming

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Model RSA
Model RSA

  • Inexpensive
  • Compatible with any transducer up to 100,000 ohms
  • Ideal for custom designed, modified, or experimental circuits
  • Fits Curtis TR1 or TR3 snap-in track
  • Works best with Curtis RS2, RS4, RS6, RS10, RS12, RS15 or RS16 relay socket assemblies
  • Operates directly with solenoids and valve actuators rated 24VDC, >250 ohms
  • Limits direct-short transducer current to 10MA/24VAC

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Model PCT
Model PCT

  • Zener diode-regulated power supply limits operating point variations to less than 0.5%
  • Sensitivity to 100,000 ohms, but extendable to 250,000 ohms
  • Potentiometer for signal sensitivity adjustment
  • Built-in time delay can be adjusted to suit customer needs
  • For light or dark energizing operations
  • Differential adjustment provided
  • Limits short circuit transducer current to 4MA/9VDC
  • Auxiliary contactor available for heavy loads exceeding capacity of plug-in relay

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Series P - Probes
Series P - Probes

  • All probes feature 316 stainless steel electrodes
  • Single, dual, or multi-probe designs in PVC or nylon
  • Up to six feet long in one-foot increments
  • Versatile
    • Five basic probe types
    • 14 model variations
  • Up to 2,500 lbs./700o F
  • Ideal for almost any pressure/temperature requirement
  • Covered probes available for unusually adverse environments

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Accessories
Accessories

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Contact Button

Operating on the principle of conductivity (the ability of a liquid to conduct electricity), Curtis Industries Liquid Level controls sense and control the level of almost any fluid or moist solid. These units are available with fixed or adjustable set points to control levels in fluids having an external circuit resistance up to 3,000,000 ohms.

In operation, two or more submerged liquid level probes pass a minute electrical current through the liquid to be controlled. This current, typically 500 microamperes, is introduced to a solid-state resistance-sending amplifier which provides sufficient gate signal to trigger a silicon-controlled rectifier (SCR). The firing threshold is accurate to within 2% of operating differential and is adjustable by means of a potentiometer. The output of the SCR is used to operate the plug-in control relay. When anticipated loads exceed that of the standard relay, an auxiliary contactor is utilized.

Control Models ELS, LCS/LHS, LCF and RSA are designed for forward mode operation. They interpret a decrease of external circuit resistance from set point as an “ON” signal. Model LCR is designed for reverse mode operation. It energizes when external circuit resistance increases above set point. Model DLC is intended primarily for pump and heater level/lockout applications. See the appropriate catalog sections for specific application information.

When selecting a liquid level control, several factors must be taken into consideration. Questions arise as to what mode of operation is required, what is the resistivity range of the fluid to be controlled, is a fixed or variable set point called for, are special functions required such as a pump or heater lockout, etc. Use the connection diagrams in the Curtis Industries Catalog to select the ideal control for your specific application.