ES-1762 Rev.6
18AT
Rack-mounted DCS Signal Conditioners 18-RACK
THERMOCOUPLE ALARM
Functions & Features
• Providing relay contact closures at preset input levels
• Direct input from a thermocouple
• Burnout protection
• High-accuracy cold junction compensation
• Single or dual (Hi/Lo) trip
• Front accessed screwdriver setpoint adjustments
• Enclosed relays
Typical Applications
• Annunciator
• Various alarm applications
MODEL: 18AT–[1][2]–R[3]
ORDERING INFORMATION
• Code number: 18AT-[1][2]-R[3]
Specify a code from below for each of [1] through [3].
(e.g. 18AT-25-R/BL)
• Temperature range (e.g. 0 – 800°C)
Use Ordering Information Sheet (No. ESU-1033) to specify alarm output code 0 specifications.
[1] INPUT THERMOCOUPLE
1
: (PR) (Usable Range 0 to 1760°C, 32 to 3200°F)
2
: K (CA) (Usable range -270 to +1370°C, -454 to +2498°F)
3
: E (CRC) (Usable range -270 to +1000°C, -454 to +1832°F)
4
: J (IC) (Usable range -210 to +1200°C, -346 to +2192°F)
5
: T (CC) (Usable range -270 to +400°C, -454 to +752°F)
6
: B (RH) (Usable range 0 to 1820°C, 32 to 3308°F)
7
: R (Usable range -50 to +1760°C, -58 to +3200°F)
8
: S (Usable range -50 to +1760°C, -58 to +3200°F)
N
: N (Usable range -270 to +1300°C, -454 to +2372°F)
0
: Specify
[2] ALARM OUTPUT
1
: Hi (coil energized at alarm)
2
: Hi (coil de-energized at alarm)
3
: Lo (coil energized at alarm)
4
: Lo (coil de-energized at alarm)
5
: Hi/Lo; N.O., OFF in power failure
(connector output not available)
6
: Hi/Lo; N.C., OFF in power failure
(connector output not available)
0
: Specify
POWER INPUT
DC Power
R
: 24 V DC
(Operational voltage range 24 V ±10 %, ripple 10 %p-p max.)
[3] OPTIONS
Burnout
blank
: Upscale burnout
/BL
: Downscale burnout
/BN
: No burnout
GENERAL SPECIFICATIONS
Construction
: Rack-mounted; terminal access via screw terminals on the front and connector on the rear; terminal cover provided
Connection
Input
: M3.5 screw terminals (torque 0.8 N·m)
Alarm output
: M3.5 screw terminals (torque 0.8 N·m) and connector
Power input
: Supplied from connector
Screw terminal
: Nickel-plated steel
Isolation
: Input to output to power
Relay
: Enclosed
Setpoint adjustments
: Multi-turn screwdriver adjustments (front); -5 – +105 % independently
Cold junction compensation
: CJC sensor attached to the input terminals (B thermocouple is without CJC as standard)
Hysteresis (deadband)
: Approx. 1 %
Front LEDs
: Red LED turns on when the coil is energized.
INPUT SPECIFICATIONS
Input
: Thermocouples
Minimum span
: 3 mV
Offset
: Max. 1.5 times span
Input resistance
: 20 kΩ minimum
Burnout sensing
: 0.1 μA
(PR): Min. Span 370°C, 670°F
K (CA): Min. Span 75°C, 140°F
E (CRC): Min. Span 50°C, 90°F
J (IC): Min. Span 60°C, 110°F
T (CC): Min. Span 75°C, 140°F
B (RH): Min. Span 780°C, 1410°F
R: Min. Span 360°C, 650°F
S: Min. Span 380°C, 690°F
N: Min. Span 110°C, 200°F
OUTPUT SPECIFICATIONS
Output
: Enclosed SPST and SPDT relays
Rating
: 120 V AC @ 1 A (cos ø = 1)
30 V DC @ 1 A (resistive load)
0.2 A maximum for the connector output
Maximum switching voltage
: 120 V AC or 30 V DC
Max. switching power
: 120 VA or 30 W (24 VA or 6 W for the connector output)
Minimum load
: 5 V DC @ 10m A
Mechanical life
: 5 × 10
7
cycles
INSTALLATION
Current consumption
: Approx. 80 mA
Operating temperature
: -5 to +55°C (23 to 131°F)
Operating humidity
: 30 to 90 %RH (non-condensing)
Mounting
: Standard Rack 18BXx or 18KBXx
Weight
: 150 g (0.33 lb)
PERFORMANCE in percentage of span
Trip point repeatability
: ±0.1 %
Cold junction compensation error
(at 20°C ±10°C or 68°F ±18°F)
K, E, J, T, N
: ±0.5°C or ±0.9°F
S, R, PR
: ±1°C or ±1.8°F
Temp. coefficient
: ±0.015 %/°C (±0.008 %/°F)
(at over 400°C or 750°F for R, S and PR; over 770°C or 1420°F for B)
Response time
: ≤ 0.5 sec. (0 – 100 % at 90 % setpoint)
Burnout response
: ≤ 10 sec.
Line voltage effect
: ±0.1 % over voltage range
Insulation resistance
: ≥ 100 MΩ with 500 V DC
Dielectric strength
: 1500 V AC @ 1 minute
(input to output or power)
500 V AC @ 1 minute (output to power)
1500 V AC @ 1 minute (input or output or power to ground)
EXTERNAL VIEW
EXTERNAL DIMENSIONS unit: mm [inch]
TERMINAL ASSIGNMENTS
SCHEMATIC CIRCUITRY & CONNECTION DIAGRAM