THE PROBLEM: After we completed the
design of the new refrigeration system for Burley's Rink Supply, their
customers began requesting enhanced controls and new operator interface
features. Some of these included:
-
Security: Customers often
contract out-of-house security services to insure that their assets
are protected. Since refrigeration equipment failure can have
serious financial implications, the client’s customers wanted an
off-premises alarm directly to the security company should a serious
malfunction occur during off hours.
- Energy: Energy consumption is
the highest cost associated with refrigeration units. Since most
facilities do not operate on a 24/7 basis, customers wanted a way to
automatically stage back the refrigeration system during off-hours
in order to reduce costs.
- Quality: Customer requirements
differ. Operators requested a feature that would allow them to
automatically adjust ice quality to accommodate their needs.
- Operation: Start up and
shutdown of ice making equipment occurs very infrequently. Mistakes
generally occur during the startup or shutdown process. These
mistakes can be serious and may result in damaged equipment. The
customers wanted a method to minimize the potential for problems
during system startup and shutdown.
- Equipment Life: Refrigeration
systems are generally sized to meet extreme operating conditions.
Under normal operating conditions, there is excess capacity that may
be used for other applications such as a supplement to the building’s
air conditioning system. However, under extreme conditions, the
combined ice sheet and air conditioning load may overly tax the
refrigeration system. The client wanted a method to automatically
offload the air conditioning system should this problem occur.
THE SOLUTION: The selection of a
programmable logic control and graphical operator interface allowed REAL
Controls to develop solutions for each of these requests.
- Security: REAL Controls developed a
PLC program to monitor critical conditions. Working with several
building security companies we developed a method to interconnect
the PLC hardware with the building security hardware. If a serious
problem occurs, an alarm is automatically transmitted to the
off-site security company.
- Energy and Quality: One way to reduce
energy consumption is to raise the temperature of the ice sheet.
However, the temperature of the ice sheet determines the quality of
the ice. REAL Controls approach to this problem was to add an ice
temperature scheduling capability to the operator interface. Using
the scheduler, the operator can select the desired ice temperature
for any hour of any day in the year. The operator interface
programmable control transmits the appropriate temperature set point
to the PLC.
- Operation: Each step of start up and
shutdown procedures requires the operator to make adjustments to
certain hand-operated devices. Using the capabilities of graphical
operator interface, REAL Controls developed interactive procedures
for initiating and monitoring equipment start up and shutdown. The
program gathers information electronically, from sensors attached to
the PLC, and automatically programs appropriate actions to achieve
proper start up or shutdown. The PLC directs the operator to make
certain adjustments and requires operator input to verify that the
correct conditions exist.
- Equipment Life: REAL Controls
installed additional valves and PLC hardware to control offloading
of the customer's air conditioning systems. The PLC program was
modified to evaluate when to offload the air conditioning system.
The PLC will automatically open or close valves depending upon the
load being applied to the refrigeration system. If the PLC
determines that it cannot maintain both the air conditioning load
and the ice sheet, it automatically disconnects the air conditioning
load from the chiller.
THE RESULTS: Each modification
enhanced the capabilities of the refrigeration system and helped the
client to better market their product. The new capabilities have
resulted in increased sales. Additional advantages include:
- Higher customer confidence and
satisfaction.
- Reduced electrical costs.
- Ability to set conditions to better
meet the customer's requirements.
- Reduced possibility of equipment
damage during start up or shutdown.
- Reduced wear on the equipment.
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