DCS and PLC and other control cabinets are inspected before leaving the factory

1. Test preparation:

1. It is necessary to remove all power switches before powering on the PLC control cabinet or IO cabinet.

2. It is necessary to completely cut off the connection between the PLC or DCS card and the outside. All front adapters are to be loosened and raised.

3. Check whether the power terminal wire and connection equipment are crimped tightly, and the false connection of the power cord will lead to the incineration of the instrument or electrical appliance.

4. Check whether the hardware settings of various instruments and electrical appliances meet the planning requirements; Check whether the power settings and circuit settings of the terminal board meet the planning requirements.

DCS and PLC and other control cabinets are inspected before leaving the factory

DCS and PLC and other control cabinets are inspected before leaving the factory

2. Power-on:

1. In terms of basic principles, it is necessary to start from the main power supply, and the power transmission will be carried out one by one. Before power transmission, check whether the voltage on the input side of the switch is normal, and whether the impedance on the output side of the switch is normal. If the resistance on the output side is small, the reason is recognized. The instruments in the cabinet do not agree to supply power to multiple instruments at the same time. After one instrument is powered on normally, put the next instrument in.

2. Before the total power supply is turned on, it should be admitted whether the communication voltage level meets the requirements. When there are two communication power incoming lines without active switching, strict attention should be paid to prevent parallel connection. When there is active switching, a no-load test should be carried out to check whether the dual-power active switching equipment is working normally.

3. After the communication power supply is normal, turn on the DC power supply, check whether the output voltage of the DC power supply is normal, and whether it is sent to the inlet side of each DC switch.

4. Check whether the DC power supply is sent to the terminals of all electrical equipment, including the power terminals of the PLC expansion module. When the review is over, you can temporarily shut down unnecessary instruments and wait for the next test.

3. Signal Injection:

1. Imitation Signal Test: When using a signal generator to inject a signal into an instrument, it is necessary to specify the nature of the injection point and the output type of the signal generator. It is not allowed to inject a voltage signal into the current signal input. Depending on the signal type (2-wire system, 4-wire system, voltage, resistance, MV, etc.) The AI input should inject the corresponding signal into the instrument signal input. Selecting the wrong signal can cause the signal generator or instrument to burn. Pay special attention to the difference between two-wire and four-wire signals. When testing the AO signal, the current signal can be injected into the front connection of the card, and the short circuit can be measured directly on the terminal with an ammeter.

2. Switch signal test

The C24V signal can be directly injected into the DC24V DI or DO point for testing, and the injected signal must be connected in series with a stable wire of less than 0.5A, including imitating the dry contact signal. When the DI input is shorted, a safe short circuit should also be used. When injecting a signal into an instrument with a live device, it is necessary to be clear about the nature of the injection point. DI card: When imitating a level signal input, a DC signal can be injected directly into the level input with a short stable wire. When mimicking a dry contact, short the input directly with a secure short wire. DO card: The signal corresponding to the voltage can be injected into the adapter at the front. Before the injection, ensure that the injection point is not energized, and use a connection cable with proper protection. It is necessary to loosen the front adapter before lifting the module.

4. Matters needing attention:

1. When the instrument or PLC is energized, it does not agree to inject a current signal into the current signal output terminal, resulting in meter burning. 2. Do not answer: Use the resistance file to measure the resistance or on-off of live equipment or components. Failure to comply with this requirement will result in the incineration of the resistance gear. 3. The precision resistance box is a signal transmission device, which can only be used as a signal source to imitate the temperature of the resistance, and other tests are not allowed to be used as a variable resistance at will. 4. The use of amperometric timing, it is generally connected in series in the circuit. If the short-circuit current is directly measured with an ammeter, it is limited to the following occasions: the four-wire current output terminal of the surface, such as the current output terminal of the safety gate, the output terminal of the PLC Cao module, and the current output terminal of the external regulation signal; The signal input terminal of the PLCAI module is used to receive a four-wire signal. When using the AI module 7KF02 of Siemens PLC, if the range block is set to D (equipped with a two-wire transmitter), it is not allowed to short-circuit the PLC terminal to measure the current. 5. When the ammeter is connected to the loop to measure the current, it should be recognized that the current range should be selected as the appropriate gear.

DCS and PLC and other control cabinets are inspected before leaving the factory

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