Theory & Sequence of Operation: Heat System

Theory of Operation: Heat System

The heat system on a Quantum open fryer has two main design purposes:

1. Gradual Heating: This system heats the oil from a cold state using pulses. This gradual heating process prevents scorching and degradation of the oil, helping to maintain its quality and extend its life. This process is used during the initial startup of the fryer or after a filtration or clean-out has been performed.

2. Temperature Maintenance: The system is designed to heat and maintain the set cooking temperatures for different products. This ensures the best quality of the cooked products, as determined by the internal programming specific to each product.

Component Overview

Main Control Board

The main Control Board monitors the temperature probe, which detects the temperature of the oil. The Control Board compares the measured temperature with its programmed set point. If the oil temperature is lower than the set point, the Control Board calls for heat and energizes the secondary contactor coils (24VAC) which energizes the heating elements. If the oil temperature is within a couple degrees or above the set point, the Control Board de-energizes the secondary contactor to prevent overheating.

Power Cords

Located at the rear, they supply line voltage to each Vat.

Circuit Breakers

Two breakers per Vat located at the rear, designed to trip in case of high amperage, over-amperage, or short circuits of the heat system.

Contactors

A contactor is an electrically controlled switch used for switching an electrical power circuit on and off. In the Quantum Open Fryer, each heating element (upper and lower) is controlled by two electrical contactors; a primary contactor and a secondary contactor. The primary and secondary contactors for the upper heating element are located to the left and the contactors for the lower heating element are located on the right when facing from the rear of the fryer. Each contactor has a 24VAC coil. When energized by the control, the contactor pulls in the contacts, allowing line voltage to power the heating elements.

Primary Contactor (Safety Contactor)

• Function: The primary contactor, also known as the safety contactor, energizes when the control is turned on. This allows voltage to reach one side of the heating element.

• De-energization: This contactor will de-energize if:

  • One of the safety mechanisms (high limit or heating element circuit breaker) trips.

  • The control is turned off.

• Cycle Frequency: The primary contactor cycles only when the control is turned on or off, or when a safety mechanism trips.

Secondary Contactor (Heat Contactor)

• Function: The secondary contactor, also known as the heat contactor, energizes to allow opposing legs of voltage to be present at the heating element. This creates resistance in the heating element, causing it to energize and heat the oil.

• Operation: The heat contactor energizes when there is a demand for heat and de-energizes when there is no demand for heat.

• Cycle Frequency: This contactor may cycle hundreds of times a day, responding to the heating demands.

Heating Elements

There are two heating elements per vat: one upper and one lower, they are the main components for heating the oil. The quantum open fryer uses fire bar style heating elements. Each contains three separate heating circuits.

• Upper Heating Circuit: Controlled by the top wires (one on each side).

• Middle Heating Circuit: Controlled by the middle two wires (one on each side).

• Lower Heating Circuit: Controlled by the lower two wires (one on each side).

High-Limit Probes

Installed on each element, these probes sense and read the temperature of the elements during heating to ensure proper temperature rate of rise and act as the main safety to prevent overheating and thermal events. Each probe contains two J type thermocouples. J type thermocouple has a pair of wires: white and red. White is connected to positive terminal and red is connected to the negative terminal at the high limit module.

High Limit Module Controls

There are 2 Module Controls per Vat, located behind the main display controls. These work with the High-Limit Probes as a safety to monitor the rate of rise of the elements and oil and will trip if temperatures exceed 575°F (300°C).

Main Temperature Probe

This probe monitors the oil temperature. The control system uses this probe to detect temperature changes that helps maintain cooking temperatures and reheating of the oil after a filtration or start up. This is a 1K ohm RTD probe.

Level Probe

Ensures the oil level is correct during the heating process. This is a 1K ohm RTD probe.

Sequence of Operation

• Line Voltage: Line voltage from the facility is routed through power cords to the circuit breakers, standing by until the main power switch is activated.

• Activation: Press the power switch to the "ON" position. This action sends 24VAC to the control board.

Safety Circuit Check

• The 24VAC is routed from the control board through the lower and upper high limit modules in a loop back to the main control board.

  • Error if this step fails: If one of the high limit modules is tripped, this interrupts the 24VAC. The main control panel will display an E-10 error.

• The 24VAC passes through the circuit breakers at the rear of the fryer.

  • Error if this step fails: If tripped, an E-30 error will be displayed. Verify that the circuit breakers are not tripped and maintain a closed circuit.

Primary Contactors Energize

• Primary Contactor Activation: The control sends 24VAC to the primary contactor to close and sending voltage to one side of the heating elements.

  • Error if this step fails: If one of the primary contactors does not energize, oil will not heat or heat slowly and the control would alert a W-7 Low Amps error.

Oil Safety Monitoring

• The control monitors resistance readings from the main temperature probe and the bottom probe to ensure the oil is safe to heat.

  • Error if this step fails: if there is a high delta difference between the main probe and the bottom probe a E-1 Low Oil error occurs.

Secondary Contactors Energize

• The main Control Board monitors the temperature probe, which detects the temperature of the oil. The Control Board compares the measured temperature with its programmed set point. If the oil temperature is lower than the set point, the Control Board calls for heat and energizes the secondary contactor coils (24VAC) which energizes the heating elements. If the oil temperature is within a couple degrees or above the set point, the Control Board de-energizes the secondary contactor to prevent overheating.

  • Error if this step fails: If one of the secondary contactors does not energize, oil will not heat or heat slowly and the control would alert a W-7 Low Amps error.

Heating Process

• Cold Startup: The control pulses heat during a cold startup to 270°F.

• Full Heat Stage: Upon reaching 270°F, the control transitions to a full heat stage until the set point is achieved. This prevents the oil from "burning" by initially heating at a lower temperature.

Temperature Display and Control

• Display Status: During heating, the control displays "WAIT" until the temperature reaches the ready range of the product set point -5°F to set point +15°F. The control prevents the operator from dropping product outside of this range.

Ready State for Cooking

• Cooking Readiness: Once the control confirms it has reached the ready state for cooking, it displays the product name (or abbreviation). The control continues to monitor the oil temperature using the main temp probe and pulses the heat on and off as needed to maintain the correct ready range temperature.

Main Cooking Process

• Temperature Compensation: During the main cooking process, the control system monitors the temperature drop from the main temperature probe. It initiates heating to compensate for this drop and restores the temperature to the set cooking point.

• Cook Time Variability: The actual cook time can vary based on the amount of product in the fryer:

  • Full Load: The compensation time will heat back up to the set point, aiming to cook the product close to the set time. However, the cook time might be slightly longer if more product is added.

  • Less than Full Load: The cook time may be shorter than programmed time because the oil temperature doesn't drop as much, leading to quicker reheating.

• Heat Compensation Settings: These settings are saved in the main programming of the products and should not be altered.