The oscillation safety protection device of the constant temperature cultivation shaker is designed around three major goals: equipment operation stability, sample safety, and operator safety. It covers multiple aspects such as oscillation system, temperature control system, and human-computer interaction. Different models of shaker protection devices have slightly different configurations, but the core protection functions are basically the same. The specific classifications are as follows:
1、 Core safety protection device of oscillation system
The oscillation system is the core power component of the shaker, and its protective device mainly prevents equipment damage and sample leakage caused by overload, imbalance, and overspeed.
The motor and transmission structure of the overload protection device shaker have a rated load range. When the total weight of the culture bottles placed on the shaker exceeds the rated value, or when the oscillation resistance is too high due to the viscosity of the sample, the overload protection will be triggered.
Working principle: Monitor the working current of the motor through a current sensor. When the current exceeds the rated threshold, the system automatically cuts off the motor power or reduces the speed; Some models are equipped with torque sensors that directly monitor transmission torque and immediately shut down when overloaded.
Function: To prevent the motor from burning out due to long-term overload operation, and to prevent mechanical failures such as belt slippage and gear wear.
Uneven placement of culture bottles (such as one side being too heavy) can cause severe shaking during the operation of the shaker, which not only affects the oscillation effect, but may also damage the equipment or cause the culture bottles to rupture.
Working principle: The vibration amplitude and levelness of the shaking table workbench are monitored through vibration sensors or displacement sensors. When the vibration amplitude exceeds the set threshold (such as amplitude deviation>20%), the system will sound an alarm and automatically stop or slow down.
Operation tip: Some models will perform a "balance self-test" before starting up. If an imbalance is detected, the startup function will be locked and the operator needs to readjust the placement of the culture bottle before starting.
The overspeed protection device prevents the oscillation speed from exceeding the set value due to the failure of speed control (such as frequency converter failure), which may cause the culture bottle to rupture due to excessive centrifugal force.
Working principle: Equipped with a dual speed monitoring module - one is to control the upper limit of the speed set by the program (users can adjust it according to their needs, such as a maximum speed of 250rpm); The second is the speed sensor at the hardware level, which provides real-time feedback on the actual speed. When the actual speed exceeds the upper limit of 10% -15%, the motor power supply is immediately cut off and an alarm is triggered.
Addendum: Some models also have a "speed gradient function", which slowly increases the speed from low to high when starting and slowly decreases when stopping to avoid sample splashing caused by sudden changes in speed.
The workbench limit and locking device prevent the workbench from shifting or falling off during oscillation, especially for large capacity floor standing rocking tables.
Structural design: The workbench is equipped with anti slip limit blocks around it, and the bottom is fixed to the transmission mechanism through locking bolts; Some models are equipped with magnetic or snap fasteners to ensure that the culture bottle tray will not slide due to severe oscillation.
2、 Temperature control system linkage safety protection device
The oscillation function of the constant temperature cultivation shaker is linked with the temperature control function. Abnormal temperature can directly affect the sample cultivation effect and even cause safety hazards. Therefore, multiple temperature control protections need to be equipped.
Overtemperature protection device (dual overheat protection) is the core protection of the temperature control system, which is divided into two layers: "software protection" and "hardware protection", to prevent sample damage or fire caused by temperature runaway.
First level protection (software): The control system monitors the temperature inside the cabin in real time. When the temperature exceeds the set value (such as the user setting 37 ℃, the over temperature threshold is set to 40 ℃), the heating tube power is automatically cut off, and the refrigeration system (if equipped) is started to cool down, and an audible and visual alarm is issued.
Secondary protection (hardware): Equipped with temperature fuses or mechanical temperature switches that are independent of the control system. When the temperature inside the cabin reaches a dangerous threshold (such as 60 ℃), even if the control system fails, the heating power can be forcibly cut off, which is the "last line of defense".
Temperature sensor fault protection: If the temperature sensor fails (such as open circuit, short circuit), it will cause temperature control to be inaccurate, and the protection device will be triggered at this time.
Working principle: The system monitors the feedback signal of the sensor. If the signal is abnormal (such as numerical jump or no signal), it immediately stops heating/cooling, locks the oscillation function, and prompts "sensor fault" on the display screen to avoid the equipment running without temperature monitoring.
The door linkage protection device prevents operators from opening the cabin door during the operation of the shaker, which may cause sample contamination or accidental injury to the shaken culture bottle.
Working principle: The cabin door and equipment control system are linked through a door magnetic switch. When the shaking table is in oscillation or heating state, if the cabin door is opened, the system will immediately pause oscillation and heating, and the display screen will pop up a "door not closed properly" prompt; After closing the cabin door, you need to manually press the "continue" button for the equipment to resume operation.
Addendum: Some aircraft models are equipped with tempered glass observation windows and heat-resistant handles for the cabin doors, which not only facilitate the observation of sample status but also prevent operators from getting burned by contact with high-temperature cabin bodies.
3、 Electrical system and overall safety protection device
This type of device ensures electrical safety of the equipment, prevents accidents such as leakage and short circuit, and is suitable for all types of constant temperature cultivation shaker.
Leakage protection and grounding protection
Built in residual current circuit breaker, when there is a leakage (leakage current exceeding 30mA) in the equipment casing or circuit, the power will be cut off within 0.1 seconds to protect the safety of operators.
The equipment must be reliably grounded (grounding resistance<4 Ω), and the grounding terminal identification must be clear to avoid the risk of static electricity accumulation or leakage caused by poor grounding.
The overcurrent and short-circuit protection electrical control system is equipped with air switches and fuses. When a short circuit or current overload occurs in the circuit, the air switch will automatically trip and the fuse will melt to prevent electrical components from burning out and avoid causing fires.
The power-off memory protection device belongs to the "sample protection" function. When there is a sudden power outage, the system will automatically save the current oscillation speed, temperature, running time and other parameters; After restoring power, the equipment can automatically continue to operate according to its original parameters, avoiding interruptions in the cultivation process due to power outages, especially suitable for long-term continuous cultivation experiments.