Overspeed protection system
What is overspeed protection?
Overspeed protection is a system for rotating machinery such as turbines, generators, and motors that detects the overspeed and excessive acceleration conditions and then acts to prevent damage and downtime. Due to the cost of turbines or other rotating machinery equipment, utilizing a reliable and safe overspeed protection system is very important.
What is turbine overspeed test?
A set point that shows the maximum acceptable speed of the rotating machine should be set in overspeed protection system. If the speed of the turbine exceeds the set point value and the trip relay or circuit acts on time, overspeed test is passed, and if not the over speed is failed. It should be noted that during the overspeed test risk of loss of load should be considered.
What is electronic overspeed?
Overspeed protection system contains several electronic-based cards such as communication, relay, voter cards, and so on. The sensor signal is read by the electronic cards of the overspeed protection system, then by comparing the set and read value, a relay can close or open control valves.
What is an electronic overspeed trip?
There are two types of overspeed trips; mechanical and electronic. In the electronic overspeed protection systems, a sensor measures the speed of rotating machinery gear and gives the system a sinusoidal or square wave, the speed has been determined by the system and thanks to the logic and trip relay section, the electronic overspeed trip mechanism is utilized. Due to the necessity of safety in these types of systems, a redundant voter structure is used.
Each rotating machinery, either heavy such as turbines and generators, or light such as diesel motors and generators, should be driven on specified condition and their rotational speed should not exceed the set value. There are a lot of crashes in the power plant and other utilities due to the rotating machinery overspeed event. Utilizing overspeed protection systems in turbine and generator units in power plants is very important because any crashing and failing of these units has a considerable cost.
Designing and implementing the overspeed protection systems is not easy in a way that designers should consider related standards such as API 670 which explains the minimum requirements for machine protection systems like electronic overspeed detection, logic and control separation, and response time. Moreover, due to the expensive equipment which is installed in power plants, oil refinery sites, and other utilities all of the protection systems should be designed and implemented by considering SIL requirements.
There are well-known companies around the world that design overspeed protection systems like Bentley Nevada, Braun, Isetec, and Emerson. The latest version of Bentley Nevada’s overspeed protection system is the 3500 machinery protection series. E16X series is the Braun overspeed protection system. Also, Woodward’s overspeed protection system is PROTECH-GII. Also, the CCC introduces its overspeed detection system as the Guardian overspeed protection system. All of the mentioned systems are utilized for generator overspeed protection, steam turbine overspeed protection, and gas turbine overspeed protection.
Rayan P-10 Product
The RAYAN-P10 Overspeed Protective Equipment is a product developed by HANI Energy Co. It is intended to be
used for rotating machines Overspeed protection.
Overspeed Protection Device reads the frequency of input sensors by 3 independent Monitoring modules and trip two 2oo3
voters if at least two sensors detect over frequency(Electronic overspeed trip) from user setpoint.
In this SIL3 overspeed protection device, each monitoring module reads two other sensors for comparison and sensor fault detection. In addition the monitoring modules support an isolated power supply for sensors that need to be powered. In this case a
current monitoring of sensor is done to detect faults of sensor(overspeed trip).
For safety path, measuring, comparison and deenergizing the shutdown relays, is tested by a self-test
process in each Speed Monitoring and Protection Systems for Rotating Equipment. If any fault detected the module would be forced to trip mode.
Electronic Overspeed Trip Device can monitor up to two shaft speeds in the same rack (2 set of 2oo3 overspeed protection can
be assembled on one rack). Each set of overspeed can be set by unique overspeed setpoints. The Monitoring
modules and voters of two sets are independent in this safety protection devices.
There is a TFT LCD and keypad Module (IM) for displaying the status of monitoring modules, alarms and
events, and also setting the user configurations. This display part is out of safety path and only used for monitoring.
A profibus communication port exists in this overspeed protective devices for sending data of IM to user system. All the displayed data on IM
module can be read in profibus, but user settings can’t be set by this port.
In addition to IM module, a powerful PC software, Raylink, connects to system through Ethernet port, for programing the user settings or read the settings recently set on system, this user friendly software enable the user to fast configuration for overspeed safety equipment.
Product Features:
– Fast reaction time to turbine overspeed trip (15msec)
– Two Internal 2oo3 voting relays
– Isolated analogue outputs with scalable ranges for each monitoring module
– Peak speed detection and display
– Front panel TFT display
– One External-trip input
– Two alarm output
– A buffered output pulse
– Independent power input (18–30 V DC) for each Module
– The input can read magnetic pickup, proximity and hall effect sensors
– Hot pluggable modules
– Up to two shaft monitoring and trip on one rack
– Alarm management and event logger consist of:
– Speed deviation between input sensors
– Check for communication loss
– Out of range Setting Input
– Speed measurement processor failure
– Routine test performance
– Power Monitoring
– Configuration via PC and front panel LCD and keypad
Speed Pickup Sensor
Rotating machinery requires speed sensing for speed control, monitoring, and Protection. Speed sensing is accomplished using a variety of technologies. Variable-reluctance based MPUs (magnetic pickups) are commonly selected because of their simplicity, reliability, and low cost. MPUs are passive probes in sense, that there are no active signal conditioning electronics in the probe. VR (passive) sensors also do not require an external supply, simplifying the overall system and increasing system reliability values.
