What Is an Integrated Smart Air Conditioning Module (SACM)?

The Integrated Smart Air Conditioning Module (SACM) is a load management device present in certain automatic transfer switch (ATS) models. The SACM helps prevent the overloading of a generator by automatically shedding and connecting HVAC loads as needed. This SACM can manage up to four air conditioners without requiring any additional equipment.

Environment

This article applies to automatic transfer switches that ship with a SACM. Many new ATS models do not have a SACM. If a load management solution is desired for ATS models without a SACM, purchasing and installing a Generac HVAC energy manager is recommended.

General overview

The internal relays of the SACM interrupt the 24 VAC thermostat control wire to disable the air conditioner in the event of an overload. The device sheds loads in the priority order of 1 to 4, with priority 1 being the highest and priority 4 being the lowest. If an overload is detected within 15 seconds of a load being enabled, that load is locked out for 30 minutes, temporarily bypassing the fault level.

Typical SACM configuration

Load shed operation

• The 4 green status LEDs will indicate when a load priority level is enabled or disabled.
• All loads are enabled when the transfer signal is off. (ATS in Utility position).
• When utility power is interrupted, T1 is deactivated. The module remains powered via Wire 194  and Wire 0. Wire 23 is not grounded at this time.
• As the generator starts, runs, and transfers, Wire 23 is pulled to ground. Once the transfer switch goes to the standby position, T1 is powered by the generator.
• The module senses that the system is on standby and disables all loads. A 5-minute timer is activated.
  • A/CI (Priority 1) load(s) are enabled after 5 minutes.
  • A/C2 (Priority 2) load(s) are enabled after 15 seconds.
  • A/C3 (Priority 3) load is enabled after another 15 seconds.
  • A/C4 (Priority 4) load is enabled after another 15 seconds.
• When an overload is detected all loads are disabled.
• Generator overload condition is determined by generator frequency. Loads are shed when the frequency is <58 Hz for 3 seconds or <50 Hz for 0.5 seconds (For 60Hz). 
• If an overload is detected within 15 seconds of a priority being enabled, that load is then locked out. The sequence will continue until all load levels have been checked (temporarily bypassing the faulting level). The level that caused the overload will not be enabled/tested again for 30 minutes. The OPCB/SACM will attempt to enable the load every 30 minutes. During enabling, if the frequency drops below specifications, the OPCB/SACM will disable again. This will continue until the frequency does not drop when the priority is enabled, the system is
  returned to utility, or the TEST button is pressed.
• When utility voltage returns, Wire 23 is released from ground and the transfer switch returns to the utility position. The OPCB/SACM will disable all loads, time out for 5 minutes and then enable all 4 priorities at the same time.

 

SACM Wiring Layout

The SACM features four connections for managing HVAC systems and generator control wiring terminals: N1, N2, T1, 0, 194, and 23. It also has N1, N2, and T1 fuses and an integrated fuse puller that uses 6.3A fuses (part # 10000005117). The A/C 1-4 LEDs illuminate when a load is enabled, and a test button is available to simulate an overload condition. The test button operates when the transfer signal is inactive.

Note: The legacy SACM used a separate fuse holder and 5A fuses (part # 073590A). The Integrated Smart Air Conditioning Module is an excellent solution for managing HVAC loads with a generator, simplifying the installation process, and ensuring the generator does not become overloaded.