The ATC-300+ is a comprehensive and multifunctional microprocessor-based ATS controller. It is a compact and self-contained panel-mounted device that is designed to replace traditional relay and solid-state logic panels. The ATC-300+ Controller provides programmed flexibility to address the needs of any system. It operates from all system voltages between 120 to 600V, single-phase and three-phase at 50 or 60 Hz. In addition, a period of no control power is provided. The controller monitors the condition of the three-phase line-to-line voltage and frequency of Source 1 and Source 2 power sources and can be programmed for single-phase operation. The ATC-300+ Controller provides the intelligence to ensure that the ATS operates properly through a series of programmed sensing and timing functions.

Product Features

  • Auxiliary relay contacts:
    • Source 1 present 2NO and 2NC
    • Source 2 present 2NO and 2NC

  • Source 1 and source 2 sensing:
    • Undervoltage / underfrequency
    • Overvoltage / overfrequency
    • Three-phase rotation protection
    • Three-phase voltage unbalance/loss

  • Pre-transfer signal contacts 1NO and 1NC
  • Go to emergency (Source 2)
  • Seven field-programmable time delays
  • LCD-based display for programming, system diagnostic and help message display
  • Mimic diagram with source available and connected LED indication
  • Time-stamped history log
  • System test pushbutton
  • Programmable plant exercise (off, daily, 7,14 and 28 day) interval selectable run time 0-600 minutes no load/load with fail-safe
  • Integral overcurrent protection (optional)
  • In-phase transition
  • Stainless steel cover for controller (optional)
  • Communications via RS-232 or Modbus through an integrated RS-485 port (optional)

  • Specs
  • Docs



Long Name:

Technical Summary

Rating Range
120 to 600V, single phase and three phase @ 50/60 Hz
Transfer Type
Switch application dependent
Switch Type
Switch application dependent

ATC Controller Specifications

Input Control Voltage
65 to 145 Vac 50/60 hZ
Voltage Measurements of Utility
Source 1 VAB Source 2 VAB
Source 1 VAC Source 2 VBC
Source 1 VCA Source 2 VCA
Voltage Measurement Range
0 to 790 VAC rms (50/60 Hz)
Voltage Measurement Accuracy
+/-2% of nominal input voltage
Frequency Measurements Of
Source 1 and Source 2
Frequency Measurement Range
40 Hz to 70 Hz
Frequency Measurement Accuracy
+/- 0.1 Hz
Undervoltage Dropout
50% to 90% of nominal voltage
Undervoltage Pickup
(Dropout +2%) to 99% of the nominal system voltage
Underfrequency Dropout Range
90 to 97% of the nominal system frequency
Underfrequency Pickup Range
(Dropout +1 Hz) to 99% of the nominal system frequency
Overfrequency Dropout Range
103 to 110% of the nominal system frequency
Overfrequency Pickup Range
101% to (dropout - 1 Hz) of the nominal system frequency
Operating Temperature Range
-20 to 70 degree C (-4 to +158 degree F)
Storage Temperature Range
-30 to 85 degree C (-22 to +185 degree F)
Operating Humidity
0 to 95% relative humidity (noncondensing)
Operating Environment
Resistant to ammonia, methane, nitrogen,hydrogen and hydrocarbons
Generator Start Relay
5A, 1/6 hp @ 250 Vac Vac 5A @ 30 Vdc with a 150W maximum load
K1, K2 Relays

10A, 1-3 hp @ 250 Vac

[email protected] Vdc
Applicable Testing
UL-recognized component
Meets intent of UL 991 & UL 1008
Meets IEC 1000-4-2, 1000-4-3, 1000-4-4
Applicable Testing Continued
1000-4-5, 1000-4-6, 1000-4-11
CISPR 11, Class A
FCC Part 15, Class A
CSS 22.2-178
Enclosure Compatibility
NEMA 1, NEMA 3R and NEMA 12
UV-resistant ATC-300+ faceplate