CN2134731Y

CN2134731Y - Protective means for solid-state relay

Info

Publication number: CN2134731Y
Application number: CN 92215697
Authority: CN
Inventors: 邓云章
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-06-15
Filing date: 1992-06-15
Publication date: 1993-05-26
Anticipated expiration: 2002-06-15

Abstract

The utility model relates to a protective device for a solid state relay, which is characterized in that an AC power line which is connected with a load is connected in series with a current transformer, wherein, both ends of a secondary coil of the current transformer are connected in parallel with a rectifying bridge circuit, the output of the rectifying bridge circuit is connected with a photoelectric coupler through filtering and current limitation, and the output of the photoelectric coupler is connected with a solid state relay through a triggering circuit. The utility model has the advantages that the current transformer which is used for over-current detection is connected with a simple circuit to conduct the switching control of the solid state relay, and thus the millisecond-stage rapid protection of the solid state relay is achieved; the utility model omits a traditional over-current protection device, so that the long service life of the solid state relay is guaranteed, and the electrical devices which are connected with the solid state relay are also protected.

Description

Protective means for solid-state relay

The utility model relates to a kind of Current Transformer and detects overcurrent, and converts thereof into the shutoff of the circuits for triggering signal controlling solid-state relay of isolation, thereby realizes the device of overcurrent protection.

Electric equipment is often because of overcurrent, overvoltage, overheated going to pot, overheated also often overcurrent cause that therefore, overcurrent protective device is absolutely necessary to electric equipment.Yet; traditional protection is to adopt overtemperature relay at inside electric appliance; fuse or fuse; when load current surpasses certain value; overtemperature relay cut off the electricity supply automatically or fuse opening with the protection electric equipment; because the development of microelectric technique; for improving the appliance switch characteristic; improve automaticity; occurred coming the switch electric equipment with ac solid relay; as still adopting traditional over-current protection method; then because of thermal relay; fuse is to second step velocity reaction that is changed to of electric current and heat; like this, reaction goes to pot solid-state relay earlier too slowly, by the protection solid-state relay; also just can protect electric equipment, Millisecond is brought up in claimed action.

For this reason, the utility model purpose is the defective that overcomes above-mentioned overtemperature relay and fuse, provides a kind of employing to be detected the protective device of the solid-state relay of overcurrent by current transformer.

The technical solution of the utility model is achieved like this, with AC power cord that load is connected on current transformer of series connection, the secondary coil two ends of current transformer rectification bridge circuit in parallel, bridge circuit output is connected through filter, current-limiting resistance and photoelectrical coupler, and photoelectrical coupler output connects solid-state relay through circuits for triggering.When load current increases; the secondary induced potential of instrument transformer increases; within the specific limits, this electromotive force and electric current are linear, and this secondary induced current is through rectification, filtering and photoelectrical coupler; trigger of photoelectrical coupler output control; in case overcurrent, trigger action disconnect solid-state relay, like this; make the solid-state relay can be, thereby realized the overcurrent protection of electric equipment because of overcurrent does not go to pot earlier.

The utility model embodiment is described in detail in conjunction with the accompanying drawings.

Accompanying drawing is a solid-state relay protective device schematic circuit.

Shown in the accompanying drawing, with AC power cord that load is connected on current transformer M of series connection, the secondary coil two ends parallel connection of instrument transformer M is by D ₁～D ₄The rectification bridge circuit that diode is formed, bridge circuit output connects filter capacitor C ₂And current-limiting resistance R ₂, regulate R ₂Size can be used for selecting different overcurrent protection values, current-limiting resistance R ₂The other end and capacitor C ₂The end diode D that is connected in parallel ₅The back is connected with photoelectrical coupler G; photoelectrical coupler G connects flip and flop generator CD4011; output is connected with the negative terminal of ac solid relay after anti-phase; solid-state relay and trigger also are connected to a reset switch K; in case electric appliance load overcurrent; the secondary induction electric current of current transformer M rises; by rectifying and wave-filtering through photoelectrical coupler G; make the flip and flop generator action; force solid-state relay to disconnect; in case overcurrent like this, solid-state relay can instantaneous disconnections, thus the electric equipment of having protected the solid-state relay as electric switch to be connected with it.

The utility model advantage is that Current Transformer detects as overcurrent; connect a simple protection circuit; change the current-limiting resistance value; can select different overcurrent protection values, like this, solid-state relay be carried out switch control; realized the quick protection solid-state relay of Millisecond; saved traditional overcurrent protection, the long-life of solid-state relay is guaranteed, the electrical equipment that is connected with solid-state relay is protected.

Claims

1, a kind of protective device of solid-state relay; it is characterized in that; with AC power cord that load is connected on current transformer of series connection; the secondary coil two ends of current transformer rectification bridge circuit in parallel; bridge circuit output is connected through filter, current-limiting resistance and photoelectrical coupler, and photoelectrical coupler output connects solid-state relay through circuits for triggering.