UPM I Unit Protection Module

Introduction

The Unit Protection Module (UPM) is a Printed Circuit Board Assembly (PCBA) designed to interface with thermostats or Digital Direct Controllers (DDC). Its primary function is to protect the compressor by monitoring various switch and sensor states. The UPM provides essential time delays and safeguards against freezing of unit water and refrigerant heat exchangers, as well as condensate overflow, provided the appropriate sensors are installed.

The ALARM output is a Normally Open (NO) dry contact. For a 24 VAC output, the R terminal must be wired to the ALR-COM terminal; 24 VAC will be available on the ALR-OUT terminal during an alarm condition. If pulse mode is selected, the alarm output will be pulsed.

The display output is exclusively for the unit diagnostic display. This output is a pulse output connected to the Unit Diagnostics Display (UDD) and pulses 24VAC when the unit enters a lockout condition.

Refer to Figure #1 for a visual representation of the UPM Single Stage module.

Specifications

General

• Power: 24VAC ± 10%, 50-60Hz, 1.4 VA standby power consumption (Single Class II 70VA or 100VA option available).
• Physical: Printed Circuit Board with plastic stand-offs.
• Environmental Operating Range: -40°F to 176°F (-40 °C to 80°C); 10% to 90% relative humidity, non-condensing. Controls are conformal coated for environmental protection.
• Weight: 0.14 lbs. (0.07 Kg).
• Listed By: UL E118867 (Recognized component in USA and Canada).

Digital Outputs

Three (3) digital outputs - relay contacts rated at 10A resistive @ 125 VAC:

• Compressor contactor: 24VAC when "ON".
• Alarm purposes dry contact (normally open dry contact) - Pulse or Constant.
• Unit Diagnostics Display (UDD) - Pulse only.

Inputs

Six (6) inputs - dedicated inputs for:

• High Pressure Control (HPC)
• Low Pressure Control (LPC)
• Water coil Freeze Sensor (FREEZE 1) 10K @ 77°F Thermistor
• Air Coil Freeze Sensor (FREEZE 2) 10K @ 77°F Thermistor
• Condensate Overflow Sensor (CON) 230 KΩ +/- 15%
• Compressor Call (Y) Signal

Status Indication

Visual (LED) status of power and alarm indication.

Protection

Surge and transient protection circuitry.

Dimensions

• Overall: 4-1/4" (width) by 3-3/4" (height) (recommended panel depth). 108mm (width) by 95mm (height) by 44mm (recommended panel depth).
• Mounting Hole: Rectangular pattern with dimensions 3-3/4" (width) by 3-1/4" (height) or 95mm (width) by 83mm (height).

This manual is for UPM board P/N# 8733 809 536.

Key to Symbols and Warnings

Key to Symbols

Specific Warnings

UPM Module Diagram

Figure #1 illustrates the UPM Single Stage module with numbered components:

• [1] Board Power LED Indicator
• [2] UPM Status LED Indicator
• [3] Water Coil Freeze Protection Temperature Selection [R30]
• [4] Air Coil Freeze Protection Temperature Selection [R24]
• [5] DIP switch bank for UPM Board Settings
• [6] Water Coil Freeze Connection [Freeze 1]
• [7] Air Coil Freeze Connection [Freeze 2]
• [8] LCD Unit Display Connection [Display]
• [9] 24VAC Power Input [R]
• [10] Compressor Contactor Output [CC]
• [11] High Pressure Switch Connection [HPC]
• [12] Call for Compressor [Y1]
• [13] Low Pressure Switch Connection [LPC]
• [14] 24VAC Power Common [C]
• [15] Condensate Overflow Sensor [COND]
• [16] Alarm Dry Contact [OUT & COM]
• [17] UPM Ground Standoff

Unit Features

Power Random Start Up

This feature prevents multiple units sharing the same electrical circuit or network from starting simultaneously. It ensures that Heat Pumps on the same circuit do not demand high inrush currents concurrently when restarting after a power failure. If the controller is powered down for more than 28 milliseconds, a random delay is initiated. In normal operation (test switch set to NO), the unit typically starts between 270 and 300 seconds after power restoration. Unit power must be completely removed for this sequence to initiate.

Anti Short Cycle Delay

This feature protects the compressor from short-cycling if the Y call is set and removed in rapid succession. The Anti Short Cycle (ASC) delay is 300 seconds on break during normal operation. If the UPM board is set to "TEST" mode via the "TEST" DIP switch (SW1), the ASC delay is reduced to 5 seconds.

Y Call

The UPM energizes the compressor's output (CC) upon receiving a "Y" call from a thermostat or controller, after any random start-up or anti-short cycle delays have elapsed. The Y input terminal requires a 24VAC signal.

High and Low Pressure Protection

The UPM monitors the state of the High Pressure Control (HPC) and Low Pressure Control (LPC) switch inputs. Both switches must be closed for the controller to energize the compressor output (CC). The CC output is only energized when these switches are closed and any applicable delays (anti-short cycle, random start-up) have expired.

High Pressure Protection

If the HPC switch is open upon a Y call, the UPM will not energize the CC output, and the compressor remains off. The fault LED will flash once (1) intermittently, indicating a High Pressure fault, and the alarm contact remains open. If the compressor is running and the HPC switch opens, the UPM shuts down the compressor output and keeps it off until the switch closes and the anti-short cycle delay expires. The controller tracks the number of HPC openings. If the switch opens a set number of times (configured via DIP switch) within one hour, the controller enters a hard lockout condition. The alarm contact closes and energizes only under this hard lockout condition.

If the high pressure fault condition persists or occurs 2 to 4 times (depending on the "LOCKOUT" DIP switch setting) within 60 minutes of the initial condition, the unit enters a hard-lockout state requiring a manual reset.

Low Pressure Protection

If the LPC switch is open upon a Y call, the UPM will not energize the CC output, and the compressor remains off. The fault LED will flash twice (2) intermittently, indicating a Low Pressure fault, and the alarm contact remains open. If the compressor is running and the LPC switch opens, the UPM keeps the compressor running for two (2) minutes. If the condition persists, the compressor shuts down, and the UPM enters a soft lockout. The LPC fault will cause the UPM to flash twice (2) times, and the alarm contact remains open.

If the LPC switch closes, the UPM will start the compressor after the anti-short cycle delay has expired and energize the compressor output. If the low pressure fault condition persists or occurs 2 to 4 times (depending on the "LOCKOUT" DIP switch setting) within 60 minutes of the initial condition, the unit enters a hard-lockout state requiring a manual reset.

Ground

The UPM controller takes its ground reference from the unit chassis, connected via the controller's metal standoff located in the lower left corner (refer to Figure #1).

DIP Switch Settings

The DIP switches are used to configure various features of the UPM:

• Lockout mode: Two (2) or four (4) strikes.
• Reset mode: Y signal or R signal.
• Alarm mode: Constant or Pulse.
• Test mode: Normal or Test operation.

Figure #2 illustrates the DIP switch layout. Table #1 details the switch configurations and their associated functionality. Factory default settings for most heat pump applications are shown, but the unit wiring diagram is the ultimate guide.

Intelligent Reset

If a fault condition occurs, a 5-minute delay on break is initiated before the unit attempts to restart. During this period, the fault LED indicates the cause. If the fault persists or occurs 2 or 4 times (depending on the LOCKOUT DIP switch setting) within 60 minutes, the unit enters a hard lockout requiring a manual reset. A single condensate overflow fault immediately triggers a hard lockout, requiring a manual reset.

Lockout Reset

A hard lockout can be reset by turning the unit thermostat off and then back on (if the "RESET" DIP switch is set to "Y"), or by shutting off unit power at the circuit breaker (if the "RESET" DIP switch is set to "R").

Selectable Alarm Mode

The UPM can be configured for a constant or pulse alarm signal.

• Constant (CONT): The UPM provides a closed contact at the alarm output until the alarm is cleared.
• Pulsed (PULSE): The UPM sequences the alarm contact with the fault LED flashes.

Test Mode (TEST)

In test mode, the ASC and Random Start time delays are reduced to 5 seconds and 10 seconds, respectively. This mode does not affect end-user equipment operation. The alarm and display relays pulse for both soft and hard lockout conditions, and both are cleared through a manual reset.

Freeze Protection

Water Side Freeze Protection: The sensor monitors refrigerant temperature near the condensing water coils. If the temperature drops below or remains at the freeze limit trip for 30 seconds, the controller shuts down the compressor and enters a soft lockout. The default freeze limit is 26°F, which can be changed to 15°F by cutting resistor R30 or the freeze 1 resistor (refer to Figure #1).

Evaporator Freeze Protection: The sensor monitors refrigerant temperature after the thermal expansion device and evaporator. If the temperature drops below or remains at the freeze limit trip for 30 seconds, the controller shuts down the compressor and enters a soft lockout. The default freeze limit trip is 26°F.

If the freeze stat fault condition persists or occurs 2 to 4 times (depending on the "LOCKOUT" DIP switch setting) within 60 minutes, the unit enters a hard-lockout state requiring a manual reset. In both freeze protection scenarios, the status LED will flash three (3) times to indicate the alarm code.

Brownout Protection

The UPM controller continuously monitors the power supply. If the nominal voltage drops below 25% of its value (approximately 18 VAC), the unit enters brownout protection mode. The compressor CC output is de-energized, and the unit enters a soft lockout mode. The controller ignores voltage drops during the first 500 milliseconds of compressor start-up to prevent nuisance alarms. Upon detecting a brownout, the fault LED flashes five (5) times intermittently as an error code. If the brownout fault condition persists or occurs 2 to 4 times (depending on the "LOCKOUT" DIP switch setting) within 60 minutes, the unit enters a hard-lockout state requiring a manual reset.

Condensation Overflow

The UPM controller monitors the drain pan for high condensate water levels using a sensor (See Figure #5). An alarm condition is identified when the sensor's impedance drops below 230KΩ +/- 15% (this feature requires the condensate sensor option). Upon sensing this resistance value, the UPM enters a hard lockout and reports the corresponding code via its status LED with four (4) flashes. To exit this hard lockout, condensate water must return to its normal level in the drain pan, and the UPM must be reset by removing power from the Y terminal (or as configured on the DIP switch). The compressor will restart after the anti-short cycle delay expires.

The condensate overflow is the only system safety (out of six) that directly triggers a hard lockout upon an initial fault condition; there is no soft-lockout state for this fault.

UPM Sequence of Operation Flow Chart

The UPM follows a sequence of checks and conditions to control compressor operation:

1. Start Condition: The process begins with a "Y1 = ON" signal. If not, a reset is required (on R or Y). If R=24VAC, the sequence proceeds.
2. Power/Sensor Check: The system checks power supply voltage (V > 18VAC) and the status of High Pressure Control (HPC = CLOSED) and Low Pressure Control (LPC = CLOSED) switches.
3. Fault Conditions: If V < 18VAC, or HPC/LPC are open, the system enters a soft lockout, records the alarm, and starts a counter (if applicable).
4. Compressor Output (CC): If all pressure and power checks pass, the system checks if CC OUTPUT should be ON.
5. Timers:
   • If CC OUTPUT is not ON, a timer starts (120 seconds). If Time > 120 seconds, CC OUTPUT turns ON.
   • If CC OUTPUT is ON, it checks for Freeze Protection (FRZ > TEMP LIMIT).
   • If FRZ > TEMP LIMIT is NO, another timer starts (30 seconds). If Time > 30 seconds, CC OUTPUT turns ON.
6. Condensate Overflow (CON): If freeze protection is active (FRZ > TEMP LIMIT is YES), it checks for Condensate Overflow (CON > 0).
7. Initial Power Up / Delays: If CON is NOT > 0, the system proceeds to Initial Power Up, followed by the Anti Short Cycle delay and then the Random Start Up delay. If the time condition (T > ASC or RS SEC) is met, CC OUTPUT turns ON.
8. Lockout States:
   • If any fault condition leads to a counter reaching the configured limit (2 or 4), a hard lockout is triggered.
   • If a hard lockout is detected, the status LED blinks a code, the display output pulses, and the alarm output activates (ON/PULSE).
   • If a fault condition does not lead to a hard lockout, the CC OUTPUT is turned OFF.

Terminology

Key terms and their definitions:

• PSC: Permanent-split capacitor motor
• EER: Energy Efficiency Ratio
• COP: Coefficient of Performance. Provides a measure of performance for heat pumps analogous to thermal efficiency for power cycles.
• ECM: Electronically Commutated Motor.
• UPM: Unit Protection Module
• WLHP: Water Loop Heat Pump
• GLHP: Ground Loop Heat Pump
• RLA: Running Load Amps
• LRA: Locked Rotor Amps
• FLA: Full Load Amps
• NPA: Name Plate Amps
• HP: Heat Pump
• Suction Pressure: Pressure entering compressor
• Discharge Pressure: Pressure leaving compressor
• (R/A): Return Air
• Recovery: Collection and storage of fluorinated greenhouse gases from products during maintenance, servicing, or prior to disposal.
• Recycling: Reuse of recovered fluorinated greenhouse gas after basic cleaning.
• Reclamation: Reprocessing of recovered fluorinated greenhouse gas to match virgin substance performance.
• Decommissioning: Final shut-down and removal from operation or usage of equipment containing fluorinated greenhouse gases.
• Repair: Restoration of damaged or leaking products or equipment containing fluorinated greenhouse gases.
• Conditioned space: Space within a building provided with heated or cooled air, or both, to maintain acceptable thermal environment conditions.

Notes

No specific notes were provided in this section of the document.