Watlow’s family of microprocessor- based limit controllers SERIES LF

Watlow’s family of microprocessor- based limit controllers

provide an economical solution for applications requiring

temperature limit control. Limits are available in a broad

range of packaging options, allowing selection of the best

version for an individual application. Controllers are

available without an operator interface and can be

ordered in square 1/8 DIN-panel mount, DIN-rail mount or

open board design configurations.

The SERIES LF limit family incorporates a microprocessor

design platform. This design provides significant

improvements in the performance, repeatability and

accuracy offered by Watlow’s current line of analog basic

temperature controllers.

The SERIES LF limit offers fixed set points and can be

supplied with or without an operator interface. Operating

set point temperature values are customer defined in the

product configuration

part number.

The LF limit controllers are factory mutual (FM) approved

with special UL® approval for the open board potted

versions. Watlow’s limit controllers include industry

leading service and support and are protected by a

three-year warranty.

Features and Benefits

Fixed set points

• Provides tamper-proof operation

Multiple mounting options

• Minimizes installation time

High or low limit with auto or manual reset

• Provides application flexibility

Fahrenheit or Celsius operation with indication

• Offers application flexibility

Sensor break protection

• Provides positive system shutdown

Agency approvals

• Meets certification requirements/compliance

Microprocessor based technology

• Ensures accurate, repeatable control

SERIES LF

Specifications

Limit Controller

• Microprocessor based, limit controller

• Nominal switching hysteresis, typically 3°F (1.7°C)

• High or low limit, factory selectable

• Latching output requires manual reset upon over or

under temperature condition

• Manual or automatic reset on power loss, factory

selectable

• External customer supplied momentary reset switch

• Input filter time: 1 second

Standard Conditions For Specifications

• Rated line voltage, 50 to 60Hz, 0 to 90% RH

non-condensing, 15-minute warm-up

• Calibration ambient range: 77°F (25°C) ±3°C

Sensor Input

Thermocouple

• Grounded or ungrounded

• Type E, J, K, T thermocouple

• >10 MΩ input impedance

• 250 nV input referenced error per 1Ω source resistance

RTD

• 2-wire platinum, 100Ω

• DIN-curve (0.00385 curve)

• 125μA nominal RTD excitation current

Input Accuracy Span Range

Type E: -328 to 1470°F (-200 to 800°C)

Type J: 32 to 1382°F (0 to 750°C)

Type K: -328 to 2282°F (-200 to 1250°C)

Type T: -328 to 662°F (-200 to 350°C)

RTD (DIN) -328 to 1472°F (-200 to 800°C)

Thermocouple Input

• Calibration accuracy: ±1% of input accuracy span,

±1° at standard conditions and actual calibration

ambient. Exception: Type T, ±2.4% of input accuracy

span for -328 to 32°F (-200 to 0°C)

• Temperature stability: ±0.3° per degree change in

ambient

RTD Input

• Calibration accuracy ±1% of input accuracy span

±1° at standard conditions and actual calibration

ambient

• Temperature stability: ±0.2° per degree change in

ambient

Allowable Operating Ranges

Type E: -328 to 1470°F (-200 to 800°C)

Type J: -346 to 1900°F (-210 to 1038°C)

Type K: -454 to 2500°F (-270 to 1370°C)

Type T: -454 to 750°F (-270 to 400°C)

RTD (DIN) -328 to 1472°F (-200 to 800°C)

Output Types

Electromechanical Relay, Form C

• Min. load current: 100mA

• 8A @ 240VAC or 30VDC max., resistive

• 250VA pilot duty, 120/240VAC max., inductive

• Use RC suppression for inductive loads

• Electrical life 100,000 cycles at rated current

External Reset Switch

• Momentary, dry contact closure

Agency Approvals

SERIES LF (potted version only)

• UL® 991 recognized temperature limit for cooking

industry

• UL® 60730-1

SERIES LF (including potted version)

• UL® 873 recognized temperature regulator

• UL® 197 reviewed for use in cooking appliances

• UL® 991

• ANSI Z21.23 gas appliance thermostat approval

• CSA C22.2 #24 approved limit control

• FM Class 3545 temperature limit switches

• RoHS, W.E.E.E.

Terminals

• 0.25 in. (6.3 mm) quick connect, push on terminal or

removable screw terminals

Power

• 24VAC +10%; -15%; 50/60Hz, ±5%

• 120VAC +10%; -15%; 50/60Hz, ±5%

• 230 to 240VAC +10%; -15%; 50/60Hz, ±5%