G168 Alarm

AC Input Field Configurable Limit Alarm – G168

Product Description

G168 Alarm

G168 Alarm

The Ultra Slim Pak G168 is a DIN rail mount, DC powered, AC voltage or current input limit alarm with dual setpoints and two contact closure outputs. The field configurable input and alarm functions offer flexible setpoint capability. Input voltage spans from 100mV to 250VAC and input current spans from 10mA to 100mA AC can be field configured. For current input spans of 1 to 5 Amps a 0.1 Ohm (5W) shunt resistor (Model# C006) is available.

The G168 is configurable as a single or dual setpoint alarm, with HI or LO trips and failsafe or nonfailsafe operation. Also included are adjustable deadbands (0.25 to 5% of full scale input) for each setpoint. The G168 will accept any DC voltage between 9 and 30VDC.

Diagnostic LEDs

The G168 is equipped with three front panel LEDs. The dual function green LED is labeled INPUT and indicates line power and input signal status. Active DC power is indicated by an illuminated LED. If this LED is off, check DC power and the wiring connection. If the input signal is more than 110% of the full scale range, the LED will flash at 8 Hz. Below 0%, it flashes at 4 Hz. Two red LEDs indicate the relay state for each setpoint. An illuminated red LED indicates the tripped condition.


The G168 is equipped with two SPDT (form C) relays, rated at 120VAC or 28VDC at 5 Amperes. Each of these relays is independently controlled by the field configurable setpoint and deadband.


The field configurable G168 limit alarm setpoints can be configured for HI or LO, failsafe or nonfailsafe operation. Each of the setpoints have a respective HI or LO deadband. In a tripped condition, the setpoint is exceeded and the appropriate red LED will illuminate. The trip will reset only when the process falls below the HI deadband or rises above the LO deadband (see Figure 1). For proper deadband operation, the HI setpoint must always be set above the LO setpoint. In failsafe operation, the relay is energized when the process is below the HI setpoint or above the LO setpoint (opposite for non-failsafe). In the failsafe mode, a power failure results in an alarm state output.

Dynamic Deadband

Circuitry in the G168 prevents false trips by repeatedly sampling the input. The input must remain beyond the setpoint for 100 milliseconds, uninterrupted, to qualify as a valid trip condition. Likewise, the input must fall outside the deadband and remain there for 100 milliseconds to return the alarm to an untripped condition. This results in a “dynamic deadband” (based on time) in addition to the normal deadband.


Unless otherwise specified, the factory presets the Model G168 as follows:


Input: Voltage
Range: 0-500mVAC
Output: Dual, SPDT
Trip: A:HI, B:LO
Failsafe: No
Deadband: A, B: 0.25%


The DC power input accepts any DC source between 9 and 30V; typically a 12V or 24VDC source is used (see Accessories).

For other I/O ranges, refer to Table 1 and Figure 4 to reconfigure switches SW1 and SW2 for the desired input type, range and function.

  • With DC power off, position input switch “SW1-9, 10” for voltage or current.
  • Set position 1 through 8 of “SW1” for the desired input range
  • Set position 1 and 2 of “SW2” to ON for a HI trip setpoint or OFF for a LO trip
  • Set position 4 of “SW2” to ON for nonfailsafe operation or OFF for failsafe operation (e.g., alarm trips when power fails).

Note: To maximize thermal stability, final calibration should be performed in the operation installation, allowing approximately 1 to 2 hours for warm up and thermal equilibrium of the system.


  1. After configuring the dip switches, connect the input to a calibrated AC source and apply power.
  2. Setpoint: set deadband at its minimum (fully counterclockwise) before adjusting the setpoint. With the desired trip input applied, adjust the setpoint until the relay trips. For HI trip calibration, start with the setpoint above the desired trip (fully clockwise). For LO trip calibration, start below the desired trip (fully counterclockwise).
  3. Deadband: Set deadband to its minimum (fully counterclockwise). Set the setpoint to the desired trip. Adjust the input until the relay trips. Readjust deadband to 5% (fully clockwise). Set the input signal to the desired deadband position. Slowly adjust deadband until the relay untrips
Relay Protection & EMI Suppression

When switching inductive loads, maximum relay life and transient EMI suppression is achieved using external protection (see Figures 2 and 3). Place all protection devices directly across the load and minimize all lead lengths. For AC inductive loads, place a properly rated MOV across the load in parallel with a series RC snubber. Use a 0.01 to 0.1uF pulse film capacitor (foil polypropylene recommended) of sufficient voltage, and a 47 ohm, 1/2W carbon resistor. For DC inductive loads, place a diode across the load (PRV > DC supply, 1N4006 recommended) with (+) to cathode and (-) to anode (the RC snubber is an optional enhancement).


Voltage Input 

  • Range: 100mV to 250VAC
  • Impedance: >100K Ohms
  • Overvoltage: 300VAC, max.


Current Input 

  • Range: 10mA to 100mA AC
  • Impedance: 20 Ohms, typical
  • Overcurrent: 200mA AC, max.
  • Overvoltage: 60V peak (protected by self resetting fuse)
  • Frequency Range: 40 to 400Hz


Common Mode (Input to Ground)

1800VDC, max.


LED Indicators 

Input Range (Green)

  • >110% input: 8Hz flash


Setpoint (Red) 

  • Tripped: Solid red
  • Safe:Off


Limit Differentials (Deadbands)     

  • >50mV/5mA: 0.25% to 5% of span
  • <50mV/5mA: 1% to 5% of span


Response Time 

  • Dynamic Deadband: Relay status will change when proper setpoint/process condition exists for 100msec.
  • Normal Mode (analog filtering): <250mSec, (10-90%)



  • Effectivity: Setpoints are adjustable over 100% of the selected input span
  • Repeatability (constant temp.): 0.2% of full scale
  • Stability Temperature: +0.025% of full scale/°C, max.



DC to 60Hz: 120dB



1800VDC between contacts, input and power


EMC Compliance (CE Mark)     

  • Emmissions: EN50081-1
  • Immunity: EN50082-1
  • Safety: EN50178


Humidity (Non-Condensing)

  • Operating: 15 to 95% @45°C
  • Soak: 90% for 24hours @65°C


Temperature Range

  • Operating: 0 to 55°C (32 to 131°F)
  • Storage: -25 to 70°C (-13 to 158°F)


Power  Consumption:

1.5W typical, 2.5W max.


Supply Range:

9 to 30VDC, inverter isolated


Relay Contacts

  • 2 SPDT (2 form C) Relays, 1 Relay per setpoint


Current Rating (resistive):

  • 120VAC: 5A
  • 240VAC: 2A
  • 28VDC: 5A
  • Material: Gold flash over silver alloy
  • Electrical Life: 10^5 operations at rated load
    • Note: External relay contact protection is required for use with inductive loads
  • Mechanical Life: 10^7 operations


Wire Terminations

Screw terminals for 12-22 AWG


Agency Approvals

  • CSA certified per standard C22.2, No. 0-M91 and 142-M1987 (File No. LR42272)
  • UL recognized per standard UL508 (File No.E99775)
  • CE Conformance per EMC directive 89/336/EEC & Low Voltage 73/23/EEC (Input <50VAC, only).



Ordering Information
1. Specify: Model: G168-0001
2. Accessories: (see Accessories)
3. Optional Custom Factory Calibration; specify C620 with desired input and output range.
All SlimPak “G” series modules will mount on standard TS32 (model MD02) or TS35 (model MD03) DIN. In addition, the following accessories are available:
HS01 Heat Sink
MD03 TS35 x 7.5 DIN Rail
WV905 24VDC Power Supply (0.5Amp)
H910 24VDC Power Supply (1Amp)
H915 24VDC Power Supply (2.3 Amp)
MB03 End Bracket for MD03
C664 I/O Descriptive Tags
C006 Shunt Resistor (0.1W, 5A max.)