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Liquid Level Control
LLC4 Series
Single Probe
Description
The LLC4 combines resistance sensing circuitry with solid state timing to provide single probe level
maintenance. On adjustable units, the sensitivity adjustment allows accurate level sensing while ignoring
foaming agents and floating debris. Isolated AC voltage is provided at the probe to prevent electrolysis. A
trickle current of less than 1 mA determines the presence or absence of conductive liquid between the probe
and common. The LLC4 Series can be used with many types of low voltage (resistance changing) transducers
to perform other control functions like temperature limit control, photo limit control, condensation sensing,
and ice sensing.
Operation
Single Probe Level
Control for Conductive
Liquids
Adjustable or Fixed
Sensing up to 250 KΩ
Selectable or Fixed Fill or
Drain Operation available
24, 120, or 230 V AC
Models are Available
Adjustable or Fixed Time
Delay Prevents Rapid Cycling
Isolated AC Voltage on
the Probes
10 A Resistive SPDT
Isolated Contacts
Approvals:
Drain (Pump Down Mode): When the liquid level rises
and touches the probe, the time delay begins. This time
delay prevents rapid cycling of the output relay and its
load. At the end of the time delay, the output relay and
LED energize and remain energized until the liquid level
falls below the probe level. The output relay and LED
de-energize and remain de-energized until the liquid
rises and touches the probe. To select this operation, the
selector knob must be rotated fully clockwise.
Fill (Pump Up Mode): When the liquid level falls below
the probe, the time delay begins. This time delay prevents
rapid cycling of the output relay and its load. At the end
of the time delay, the output relay and LED energize and
remain energized until the liquid level rises and touches
the probe. The output relay and LED then de-energize
and remain de-energized until the liquid level again
falls below the probe level. To select this operation, the
selector knob must be rotated fully counterclockwise.
Connection
Adjusting Sensitivity: On adjustable units increase the
sensitivity setting to sense (control) less conductive liquids. For example: pure water exhibits low conductivity,
requiring a higher sensitivity setting.
Relay contacts are isolated. Dashed lines are
internal connections.
Connect common to conductive tank. Additional
probe is necessary for non-conductive or insulated tanks.
P = Probe
C = Probe Common
LED Operation with Diagnostics
Accessories
Panel mount kit
P/N: BZ1
Octal
8 pin socket
P/N: NDS-8
Indicating Operation
Type
Relay Energized &
Conducting
Blinks OFF
Relay Energized
ON steady
Standard
Operation
Time Diagram
V = Voltage
With Diagnostics
(D-Suffix)
Conducting or Timing
Flashing
Relay De-energized
Power Applied &
Double Blink
Not Conducting
Relay De-energized
Ordering Table
Hold down clips
P/N: PSC8
LLC4
Series
X
Input
X
Time Delay
(Seconds)
–2 - 24 V AC –A - Drain
–Specify fixed delay
–4 - 120 V AC –B - Fill
(1 ... 60) secs. in
–6 - 230 V AC –S - Selectable
1 s increments
on unit
Electrode
P/N: PHST-38QTN
X
Operation
X
Sense Resistance
X
LED Operation
–A - Adjustable (1...250k) –Blank - Standard
LED Operation
–F - Fixed
–D - LED Operation with
Specify fixed
Diagnostics
resistance (1 ... 250)
in 1K Ω increments
9.6
1TRC 001 009 C0202
Low Voltage Products & Systems
ABB Inc. • 888-385-1221 • Technical assistance 800-377-7722 • www.ssac.com
LLC42B03
See accessory pages for
specifications.
LLC44S5AD - 120VAC, selectable fill or drain operation, time delay fixed - 5 s, adjustable sensing
resistance, LED operation w/ diagnostics
LLC44A5A - 120VAC, drain operation, time delay fixed - 5 s, adjustable sensing resistance (1...250K ohms)
LLC42S5F50D - 24VAC, selectable fill or drain, time delay fixed - 5 s, sensing resistance fixed - 50k ohms,
LED operation w/ diagnostics
05.06.10
Example P/N:
Level probe P/N: LLP-24
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Liquid Level Control
LLC4 Series
Single Probe
Technical Data
Control
Type
Sensing Voltage
Sensing Resistance
Sensing Resistance Tolerance
Operation Selection
Time Delay
Range
Input
Voltage
Tolerance
ON/OFF (Single Level) Resistance sensor with built-in time delay to prevent rapid cycling
Low voltage AC between probe and common. Isolated from Input and Output.
Factory fixed or adjustable to 250K Ω
Adjustable - guaranteed range
Factory fixed +/-10% or 500 ohms whichever is greater
Factory fixed or adjustable - Drain = rotate fully clockwise; Fill = rotate fully counter-clockwise;
Partial rotation (15% to 85%) rotation of selector dial should be voided
Fixed 1...60 s in 1 s increments (see Ordering Table)
24 V AC
120 & 230 V AC
Frequency
Output
Type
Form
Rating
Max. Switching Voltage
Life (Operations)
Protection
Surge
Isolation Voltage
Mechanical
Mounting
Termination
Package
Environmental
Operating Temperature (Surrounding air)
Storage Temperature
Weight
24, 120, or 230 V AC
-15% ... +20%
-20% ... +10%
50 ... 60 Hz
Isolated relay contacts
Single pole double throw SPDT
10 A resistive at 125 V AC
5 A resistive at 240 V AC & 28 V DC
1/4 hp at 125 V AC
250 V AC
Mechanical - 1 x 107; Electrical - 1 x 105
IEEE C62.41-1991 Level A
≥ 1500 V RMS between input, output, & probe
Accessory octal socket (NDS-8 or equivalent) required
8 Pin plug-in
2.91 x 2.39 x 1.78 in. (73.9 x 60.7 x 45.2 mm)
-25°C ... +60°C
-40°C ... +80°C
≅ 6 oz (170 g)
Diagnostic LED Operation - LLC4
Operation
Level
Diagram
LED Operation
or Mode
Level of Liquid
Power Applied & Relay De-energized
Drain
Fill
6
N/A
Low liquid level, not touching probe, end of time delay & drain cycle
N/A
Conducting & Relay De-energized
Drain
Fill
N/A
1
N/A
High liquid level, touching probe, end of time delay & fill cycle
Relay Energized & Not Conducting
Drain
Fill
5 to 6
3
Time delay in progress, liquid level dropping
Low liquid level, not touching low probe, beginning fill cycle
Relay Energized & Conducting
Drain
Fill
5
2
Liquid touching probe, start of drain cycle
Liquid touching probe, time delay in progress, liquid level rising
Mechanical View
Level Diagrams
LLC42B03
1
2
4
5
3
6
05.06.10
Inches (Millimeters)
Low Voltage Products & Systems
ABB Inc. • 888-385-1221 • Technical assistance 800-377-7722 • www.ssac.com
9.7
1TRC 001 009 C0202