Differences in the output form of Mitsubishi PLC

Generally, there are three types of Mitsubishi PLC output circuit methods, namely: relay output type, transistor output type and thyristor output type. So what are the characteristics of each of them?

Differences in the output form of Mitsubishi PLC

Differences in the output form of Mitsubishi PLC

First, the relay output circuit

PLC using relay output circuit: The contacts and coils of the relay electrically isolate the internal circuit of the PLC from the external load circuit. In addition, the output circuit method can be used as an external power supply for DC current, and it can also be exchanged. It is necessary to submerge the Mitsubishi plc relay output circuit, and the promised load is generally AC250V/50V, the load current is up to 2A, and the capacity is up to 80-100VA (voltage × current), so the output of the plc does not meet the direct starting of high-current loads (generally, small loads are used to start large loads. For example, the output of a PLC is able to be connected to a central relay with a relatively small current, which is then turned up by a large load relay angle touch, such as a bell coil.

The operating life of the relay contacts in the PLC relay output circuit method is also controlled (generally hundreds of thousands of placements, depending on the load, e.g. the life of the docking induction load is less than that of the resistive load). The relay output is also placed relatively slowly (10ms) with a destination time. Therefore, it is not appropriate to use this type of circuit output in a context where there is a desire to reach a common situation (it may be expected to apply the two output methods at the bottom depending on the local context).

When docking the inductive load, in order to prolong the service life of the relay contact, when it is closed with the external DC power supply, it is generally necessary to add a voltage push diode at the load end; When switching loads, RC should be added on the load side. Plug.

Second, the transistor output circuit

The transistor output PLC is electrically connected by a photocoupler to turn off the transistor to conduct an external load circuit and electrically separate the circuit from the transistor output circuit.

The transistor operates as a variable switch depending on the output voltage and manipulates the outgoing current. As a result, transistors can be used to turn on and off currents, and the opening and closing of the common circuit board do not coexist, because the transistors are controlled by electrical signals, and the switching speed can be very fast, and the switching lab can reach speeds above 100 GHz.

The transistor output circuit method is superior to the relay output (generally less than 0.2 ms) for the shock desire common field; Since the transistor has no hysteresis touch, it has a longer life than the relay output circuit. One aspect of the limitation of the use of transistor output circuits is that the external power supply can only be a direct power supply. In addition, the output of the transistor can be less than the relay output, the load voltage is generally DC5V-30V, and the load current is 0.2A-0.5A. These two points should be refuted when the transistor output circuit approach is applied.

Third, the bidirectional transistor output circuit

The bidirectional thyristor output circuit can only change the load at the beginning, and the total ambiguity is also faster than that of the relay output circuit, and the life is longer. The output power of the bidirectional thyristor is less than that of the relay. The load voltage is generally AC85-242V; The single-point output current is O.2A-0.5A. When multiple points share the same mass, the output current at each point should be reduced. Small (e.g., the single-point engine is 0.3A bidirectional thyristor output, when sharing the popular end at 4 o'clock, the maximum promised output is 0.88/4 points.) Note: In order to maintain the thyristor, the two ends of the thyristor in the PLC are often connected to the RC RC receiver (generally 0.015uF/22Ω placement) and the varistor, so when the thyristor is closed, the output of the PLC still has an open-circuit leakage current of 1-2mA, which may cause some small relays in the PLC to fail to seal when the output is closed.

Differences in the output form of Mitsubishi PLC

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