Encoder for water conservancy steel gate！

Encoder for water conservancy steel gate

Sluice gate control, related to flood control, drainage, water, sewage, through the ship, power generation and other applications, it is increasingly important to control security, and now has been designed to require manual emergency control now with the remote automatic control should be considered individually, and For absolute multi-turn encoders use, no longer uses the incremental value encoder or single-turn absolute encoder, the industry also has almost standardized. In the past, sluice control, absolute multi-turn encoder mostly selected SSI (synchronous serial) output signal, and now under design safety requirements, encountered two difficulties:

One. Two difficulties original SSI encoder

1. SSI signal hand, since the control can not be independent.

    SSI signal to the serial signal clock synchronization, point to point transmission, the clock signal is sent and received only the same device as the PLC signal, if the encoder signal is connected to the gate opening instruments now, you can not give automatic control, but only by the gate the opening of the instrument and then the output signal to the PLC, so that the reliability of the system are based on the gate opening device, while SSI gate opening instrument high prices, manufacturers of good and bad, there is a big security risk; if the encoder signal output directly to the PLC, only a few European brands PLC have SSI interface, such as Siemens S7-300 (S7-200 would not), this high cost, less surface optional, but now manually control signal to rely on automatic control PLC to lose the significance of manual emergency control.

2. SSI signal port can not be inserted into the mine, easier to be damaged.

    SSI signal is "synchronous" serial signal, is not fully synchronized, it transmits the clock to the receiving device by the encoder, the encoder then sends a signal to the receiving device, the internal "sync" comparison, there is a synchronization time difference range requirement, once inserted mine, or a longer cable, the cable is not professional, synchronization signal exceeds the tolerance range, the data will be hopping code, and can not work properly. Our research and development over the past years, SSI mine, in the experimental stage can meet the synchronization error range, under field conditions, are often unable to ensure the synchronization of the SSI signal and hop yards, but had to give up. Unable to join the signal mine, SSI encoder being broken every year the number of many, including the famous German brand, such as Jiangsu Sanhe, using 63 well-known German brand SSI encoder, broken by lightning each year approximately 3-5 a.

II. Solution absolute encoder dual output signal

    In order to solve the above problems, the Three Gorges Hydropower Station is the use of two sets of gate opening sensor as a backup, so for most gate control is unrealistic. In discussions with the multi-national water resources design institutions and owners, we launched a dual-output true multi-turn absolute value encoder for gate opening instrument's hand, and redundancy control since independence,
    DOX58 ..- L true multi-turn absolute value encoders, double signal output for the traditional 4-20mA and RS485 bus signal, these two signals have almost all of the PLC can be connected to the interface, and the connection of the instrument is also available from Most formal instrument manufacturers to find.

Features of this program are as follows:

    1. DOX58 ..- L encoder is a mechanical gear really multiturn absolute encoder, DIMENSIONS complete with the original German import the same SSI encoder can be a direct replacement for the installation. Encoder housing protection class IP67, temperature rating of -40 degrees -80 degrees, in line with water conservancy wet, high temperature use.

    2. Dual output signal is 4-20mA and RS485, can transmit 400 meters -1000 m (depending on cable), in line with the requirements of direct remote; these two signals has a mature, a lot of mine has been used, the signal port (either an encoder or the receiving device) may play a protective role.

    3. All PLC can have 4-20mA interfaces, most of the PLC can also be connected RS485 signal, so for the optional side PLC would greatly increase the cost can be down; and 4-20mA and RS485 signals can also find the standard mature instrument, in order to increase reliability of the instrument and reduce costs. PLC and instrumentation, you can choose mutual use 4-20mA signal or RS485 signals.

    4. The encoder signals into dual manual local control with automatic PLC control, two sets of controls can be used independently, but also mutual redundancy control security can be greatly enhanced, and the cost but can be declined. Because you can increase the installation of mine, future maintenance costs for spare parts also declined.

Three. Discussion Reference:

     1. Load protection control. Since a considerable number of winch hoist load protection needs, also selectable 4-20mA output load sensor, in this scenario, the gate opening instrument can use two inputs of 4-20mA input instrumentation.

     2. hoist machine. This program not only can be used to sluice gate opening instrument control, also can be used for all kinds of safety requirements for hoist machine height control, such as iron and steel plant blast furnace feed control car (there are success stories).

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