Foundation Lockout Safety Device (LSD)

Lockout Safety Device (LSD)

Summary:

This device monitors compressor safety switch trips to prevent short cycling, protecting the compressor.
After a fourth safety switch trip, a manual reset is required within 6 hours.

LED Indicator

• Lockout is indicated by a solid (non-flashing) Red LED.
• LED will be flashing to indicate that a Safety Input has opened while a Y Call is present.

Safety Device Trip

• A Safety Device Trip occurs when the Y signal is applied to the control, but the SI is sensed as open when the Compressor Contactor Output is energized. If the Compressor Contactor Output is not energized while a Y signal is applied and the SI is sensed as open, this will not count as a fault but will not allow the Compressor Contactor to energize.

Anti-Short Cycle

• If the Y signal is applied to the control, then if either the Y signal or SI signal is removed from the board for at least 33 milliseconds, the output to the Compressor Contactor will be held off for a fixed time of 3 minutes.
• If a device safety trip is sensed at the moment the Anti-Short Cycle Timer expires (even if the Compressor Contactor Output was not energized), the control will increment the Safety Device Trips Counter and go into either another Anti-Short Cycle or a Lockout (depending on the new Safety Device Trips Count).

Compressor Lockout

• If the unit experiences four safety device trips within 6 hours (the Unit reads open on the SI while a Y call is present), it locks out and requires a manual reset (power cycled on R input). Lockout is indicated by a solid (non-flashing) red LED.

LSD Device Additional Info

• If the R + Y + SI has 24 volts at power-up, the CC output will energize immediately. 
• If the R + Y + SI have 24 volts, removing and reinstalling C does not count as a trip, and there is no 3-minute delay for the CC output to re-energize. (for example, it will cycle on the frostat opening and closing all day long) 
• If there is an R + Y at power-up with the SI open, and after 3 minutes, you apply 24 volts to SI, the CC output will come on immediately. 
• The SI open time counts towards the 3-minute delay. For example, if the SI input opens for 2 minutes and then closes, 1 minute later, the CC output will energize.

This is a representation of the current Factory LSD wiring.

Below is a typical unit wiring diagram (with only the LSD Circuit shown)

Current Factory LSD Circuit(s) wiring.

Change the LSD circuit wiring to this configuration and the contactor pulls in strong, even with high resistance in the field wiring between the unit the thermostat.

Procedure

Circuit 1 - Unplug DTL1 from wires 140B & D

Circuit 2 - Unplug DTL2 from wires 141F & G

Connect wire from LSD2 "R" Terminal (LSD1 on single circuit machines) to DTL2 then DTL1

LSD Circuit(s) after wiring change.

WARNING:

Information in this article is intended for use by individuals possessing adequate backgrounds of electrical and mechanical experience and who comply with all federal, state, and local laws, rules, orders, or regulations related to the installation, service, or repair of a heating or central air conditioning product. Any attempt to install, service, or repair a heating or central air conditioning product may result in personal injury and/or property damage. The manufacturer or seller cannot be responsible for the interpretation of the information contained herein, nor can it assume any liability in connection with its use.