Theory of Operation The RTF Manufacturing RCS-3200-ULT is a unique freezer in that it has the ability to be both a rapid pull down freezer as well as a traditional life science storage freezer along with providing an on-board back up refrigeration system. The unit is equipped with two fully complete and independent refrigeration systems that can work in tandem for maximum BTU removal or independently in normal operating mode or serve as a back up in the event of failure. The unit is set up to cycle between refrigeration systems (Systems 1 and 2) approximately every 3 hours to allow both systems to share the duty cycle and to stay functional. The refrigeration system that is the primary system during the timed operating window, will cycle on and off as the set point is satisfied. The switching of systems occurs only on time. The unit is set at approximately 3 hours as the factory default but it is fully adjustable. The unit’s controller can be set up to function based on two primary methods. (1) Deviation function, is a value that is entered into the controller based primarily off of the unit’s set point for temperature and alarm functions. Essentially it will be a range that works off of the setpoint. For instance, if you have a setpoint of -75C via a deviation of 5 degrees, this 5 degrees will be applied to high and low alarm so as the setpoint changes for all parameters based on the deviation amount. (2) Direct setpoint function will control the units based on the programmed temp for each parameter entered into the controller. We use a combination of both Deviation and Direct setpoint. The factory default set temperature is -75C. The audible alarm and remote outputs for alarms are initiated based on Direct Setpoints and have been programmed to have the warm alarm at -67C and the cold alarm at -80C. The fail safe back up is programmed via Deviation and the fail safe system is set to energize the idle refrigeration deck with a deviation from set point of 5 degrees or -70C. If the unit would warm up for any reason to -67C, the audible alarm would sound and the remote dry contacts energized to send a signal to the remote monitoring station if wired in this fashion. If the temperature would warm up to -70C, the other refrigeration system would energize and both refrigeration systems will work together to pull the temperature down to the set point of -75C as rapidly as possible. Once the temperature is satisfied, the system will return to normal operation on one of the refrigeration systems based on what unit is specified during its 3 hour operating window. The alarm once triggered, will need to be manually reset so as to inform operations personnel of the problem and to begin troubleshooting. This reset can be done once the unit reaches -74C from the “EZ button” on the bottom left front control panel. In addition, there is a separate switch to the left of the controller that can mute the audible alarm when there is an alarm condition. It is important that this alarm switch be returned to the “alarm activated” position after the alarm condition has been addressed otherwise you will not have the audible alarm for future events. Voltage 208-230 VAC 60 Hz 3 phase is required (see equipment nameplate located behind service door on right hand side of unit) for amperage requirements. Factory Settings for RCS-3200 Freezer is shipped from the factory with the following settings: Set point -75C Warm alarm -67C Cold alarm -80C Fail Safe mode to engage back up refrigeration system at -70C (5 degree deviation from setpoint) Hysteresis programmed at 1C offset Unit is in “auto mode” with both compressor switches in the “on” position Door ajar delay is 2 minutes Cycle time between switching refrigeration systems is 3 hours Cabinet Exterior: 120″ Wide, 46″ High, 34″ Front to Back Cabinet Interior: 70″ Wide, 33″ High, 24″ Front to Back To Start Up Unit The key switch is in off position from the factory. After power is applied, turn switch to the “on&dquo; position and remove the key. The unit will pull down to factory setting of -75C in approx 2 to 3 hours. Both refrigeration systems will be engaged for rapid pull down. You will need to turn the alarm switch to the “OFF” position (middle position) while the unit is cooling down to avoid hearing the audible alarm. MAKE SURE YOU PUT THE SWITCH INTO ALARM ACTIVATED MODE (up position) AFTER UNIT ACHIEVES TEMPERATURE. **Sublids should be installed before unit is energized. These are shipped loose and are packaged in the bottom of the freezer or separately. Control Function To change set point, move the arrow key to raise or lower set point. It is important to remember that other set points are relative to the default setting of -75C Alarms engage at direct setpoint entered values. (-67C warm, -80C cold) Fail safe system activates at 5 degrees from set point (-70C) 1. Output 1 on the display indicates that the control is calling for cooling. 2.Output 2 on the display indicates that the temperature has reached -74C and the staging relay has been energized, this starts the timing cycle to switch the compressor run time between system #1 and system #2 which is approx 3 hours. 3. Output 3 on the display indicates that there is an alarm condition, the display will also be flashing “alhy3” the alarm initiates when the temperature warms to -74C and the control will allow the user to manually reset the alarm by pushing the “EZ” zone key on the front of the control after the freezer reaches -76C. This will reset the alarm function and restore the display to normal. If the manual alarm rocker switch was put into the off position, it will need to be put back into the up position which is Alarm Activated mode. The “set up” features for the controller indicate how to change the alarm trip points but it is recommended to consult with RTF before doing so. Door Ajar Switch The door ajar switch is located on top left side of the freezer and is depressed by a flange on the lid. It is a small white push button. Once the lid is open, this switch will activate an “audio alarm” after a two minute time delay (this delay is adjustable up to 10 minutes). The timing starts when the door is opened. If the switch is depressed again once the lid is open, this will continue to reset the delay for 2 minutes when pushed. This could be helpful when loading the unit and to avoid alarms. Location depicted on picture #3. Battery Back-UP Power Failure Alarm The RCS units are equipped with a battery back up to energize the audible alarm in the event of a power failure. In addition, it will power the remote alarm switch (normally open/closed contacts) to send a signal to a remote monitoring location if the unit is wired for this functionality. Settings for Refrigeration systems on back of unit – Auto mode (Factory Default) Caution: These switches should only be changed by service personnel. Required Maintenance 1. Clean intake air filter every 30 days – minimum 2. Check for tube vibration at time of p/m 3. Check for free fan operation at time of p/m 4. Blow out air cooled condenser at time of p/m 5. Check for visible oil leakage 6. Check for visible discoloration to electrical components Do not connect gauges to refrigeration system Do not remove oil fill plug Download a PDF version of the RTF RCS-3200-ULT Quick Reference Guide