Zetav is a tool for verification of systems specified in RT-Logic language.
Verif is a tool for verification and computation trace analysis of systems described using the Modechart formalism. It can also generate a set of restricted RT-Logic formulae from a Modechart specification which can be used in Zetav.
With default configuration file write the system specification (SP) to the sp-formulas.in file and the checked property (security assertion, SA) to the sa-formulas.in file. Launch zetav-verifier.exe to begin the verification.
With the default configuration example files and outputs are load/stored to archive root directory. But using file-browser you are free to select any needed location. To begin launch run.bat (windows) or run.sh (linux / unix). Select Modechart designer and create Modechart model or load it from file.
The maximum allowable refrigerant leak rate per year for commercial refrigeration under EPA Section 608 (with 50+ lb charge) is: a) 15% b) 20% c) 25% d) 35% Section 5: Safety & Best Practices 13. When recovering refrigerant from a system with a burned-out compressor, you should: a) Recover into the same tank as good refrigerant b) Use a filter drier in the recovery line c) Vent the non-condensables to speed recovery d) Skip recovery if the system is under 5 lbs
The primary purpose of the accumulator is to: a) Store liquid refrigerant b) Prevent liquid slugging to the compressor c) Filter debris from oil d) Increase subcooling Section 2: Electrical & Controls 4. A potential relay is commonly used with which type of compressor motor? a) PSC b) CSIR c) CSCR d) Shaded pole
A reach-in freezer with hot gas defrost has frost only on the last pass of the evaporator. This indicates: a) Undercharge of refrigerant b) Defrost termination failed open c) TXV stuck open d) Non-condensables in the system cfesa refrigeration practice test
A defrost termination thermostat is wired in series with the: a) Evaporator fans b) Compressor contactor coil c) Defrost heater d) Liquid line solenoid Section 3: Troubleshooting & Diagnostics 7. A walk-in cooler has low suction pressure, low superheat, and a starved evaporator. The most likely cause is: a) Overcharge of refrigerant b) Liquid line restriction c) Bad compressor valves d) High evaporator fan speed
Superheat is measured at the: a) Condenser outlet b) Evaporator outlet c) Receiver inlet d) Compressor discharge The maximum allowable refrigerant leak rate per year
A compressor draws locked rotor amps immediately on start and trips the internal overload. The first step is: a) Replace the compressor b) Check for electrical short to ground c) Check for mechanical seizure d) Measure start capacitor microfarads Section 4: Commercial Refrigeration Specifics 10. In a multiple-evaporator supermarket rack system, oil return to the compressor is maintained by: a) Oil separators and timed oil return valves b) High hot gas pressure c) Continuous compressor operation d) Low superheat settings
A system with high discharge pressure and normal suction pressure could indicate: a) Dirty evaporator coil b) Low refrigerant charge c) Non-condensables or dirty condenser d) TXV bulb losing its charge a) PSC b) CSIR c) CSCR d) Shaded
Here’s a for the CFESA Refrigeration Practice Test , designed to mirror the types of questions you’ll encounter on the Certified Food Equipment Service Association exam (refrigeration section). CFESA Refrigeration Practice Test – Sample Questions Section 1: Basic Refrigeration Cycle 1. In a vapor-compression refrigeration system, the component where refrigerant gives up its superheat and latent heat is the: a) Evaporator b) Compressor c) Condenser d) Metering device
The Zetav verifier expects the input RRTL formulae to be in the following form:
<rrtlformula> : <formula> [ CONNECTIVE <formula> ] ... <formula> : <predicate> | NOT <formula> | <quantifiedvars> <formula> | ( <formula> ) <predicate> : <function> PRED_SYMB <function> <function> : <function> FUNC_SYMB <function> | @( ACTION_TYPE ACTION , term ) | CONSTANT <quantifiedvars> : QUANTIFIER VARIABLE [ QUANTIFIER VARIABLE ] ...Where predicate symbols (PRED_SYMB) could be inequality operators <, =<, =, >=, >, function symbols (FUNC_SYMB) could be basic + and - operators, action type (ACTION_TYPE) could be starting action (^), stop action ($), transition action (%) and external action (#). Quantifier symbols (QUANTIFIER) could be either an universal quantifier (forall, V) or an existential quantifier (exists, E). Connectives (CONNECTIVE) could be conjunction (and, &, /\), disjunction (or, |, \/), or implication (imply, ->). All variables (VARIABLE) must start with a lower case letter and all actions (ACTION) with an upper case letter. Constants (CONSTANT) could be positive or negative number. RRTL formulae in the input file must be separated using semicolon (;).
V t V u (
( @(% TrainApproach, t) + 45 =< @(% Crossing, u) /\
@(% Crossing, u) < @(% TrainApproach, t) + 60
)
->
( @($ Downgate, t) =< @(% Crossing, u) /\
@(% Crossing, u) =< @($ Downgate, t) + 45
)
)
Verif tool does not deal with direct input. Examples are load from files with extension MCH. Those files are in XML and describes model modes structure and transition between modes. There is no need to directly modify those files. But in some cases it is possible to make some small changes manualy or generate Modechart models in another tool.
If you have further questions, do not hesitate to contact authors ( Jan Fiedor and Marek Gach ).
This work is supported by the Czech Science Foundation (projects GD102/09/H042 and P103/10/0306), the Czech Ministry of Education (projects COST OC10009 and MSM 0021630528), the European Commission (project IC0901), and the Brno University of Technology (project FIT-S-10-1).