CN2205074Y

CN2205074Y - Little power single phase motor protector

Info

Publication number: CN2205074Y
Application number: CN 93239164
Authority: CN
Inventors: 刘越
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-08-20
Filing date: 1993-08-20
Publication date: 1995-08-09
Anticipated expiration: 2003-08-20

Abstract

The utility model relates to a protecting device for small power single phase motors, which is mainly composed of a current sampling detection circuit, a time delay relay circuit, an overcurrent protection circuit and a power supply, wherein, the current sampling detection circuit is composed of a current-limiting resistor R3, a sampling resistor R5 and controlled silicon SCR, and the time delay relay is composed of an R2, a C1, an integrated block NE555 and a relay J. When overcurrent doesn't occur to a motor, the utility model does not work. When overcurrent occurs to the motor, the controlled silicon SCR is switched on to switch on the power supply of the time delay relay to cut off the power supply of the motor. The utility model has the advantages of simple structure, low cost and small volume. The protection point of the utility model can be accurately and conveniently adjusted. The utility model is suitable for the protection of the starting, the overload and the overcurrent of small power motors.

Description

Little power single phase motor protector

The utility model relates to the emergency protective circuit device, the single-phase motor protecter of a kind of small-power.

The single-phase electric motor protective device of existing small-power is still rare; wherein a kind of to use more be bimetallic overcurrent temperature relay, and it is serially connected in the circuit that will protect, and electric current produces thermal effect on bimetal leaf; when overcurrent; heat increases, and bimetal leaf thermal deformation and the contact on the sheet metal is disconnected is because by the action of thermal deformation execute protection; hysteresis quality is big; overcurrent action point tolerance is big, and the setting of overcurrent operating point is difficult, therefore with the poor reliability of the supporting protection of all kinds of monophase machines.

The purpose of this utility model provide a kind of simple in structure, volume is little, cost of manufacture is low, the single-phase electric motor protective device of the small-power of reliable in action, to realize starting, overload, overcurrent protection.

The purpose of this utility model reaches by the single-phase motor protecter of following small-power.It mainly is made up of current sampling testing circuit, time delay relay circuit, overcurrent protection executive circuit and rectification power circuit.The current sampling testing circuit is made up of current-limiting resistance R3, sample resistance R5 and controllable silicon SCR, and R5=SCR trigger voltage/motor allows minimum overcurrent value, and the R5 value is the over-current protection point of setting.Allow minimumly when crossing flow valuve when motor working current increase to surpass motor, the voltage of the last generation of R5 is just greater than the SCR trigger voltage, the controllable silicon conducting.Time delay relay circuit by resistance R 2, capacitor C 1, the time base integrated package NE555 and relay J forms, R2, C1 determine delay time, R2 can change delay time by adjusting.The overcurrent protection executive circuit is made up of diode D3, resistance R 4, capacitor C 3, relay tip.The normally closed contact J1 of relay J and motor joining are in circuit; C3 is in order to J1 moment disconnection arc extinguishing; D3, R4 provide a voltage of keeping conducting to the SCR trigger electrode when J1 disconnects, the adhesive stably to avoid the frequent clutch of J1.The normal opened contact of J is in order to realize the self-locking of time-delay relay, and diode D2 is the release loop of relay coil.Diode D1, resistance R 1, capacitor C 2 and voltage-stabiliser tube DW have formed rectified current.When motor not during overcurrent, this device is not worked, and during over current of motor, starts working and cuts off motor power by the requirement of motor overload allowed band.

Accompanying drawing is the utility model electricity principle and embodiment circuit diagram, wherein:

D1, D3-2CP18A, the DM-low-power machine,

D2－2CP12A，R1－2×2K／3W，

DW-12V, the 0.5W voltage-stabiliser tube, R2-chooses by actual requirement,

C1-electrochemical capacitor 50 μ/16V, R3-50 Ω/0.125W,

C2－330μ／25V，R4－12K／3W，

C3-0.047 μ/630V, R5-power and resistance are made J-JQX type 12V on request, 12mA, base integrated package during IC-NE555, SCR-small-power controllable silicon 100mA/400V.

Be described further below in conjunction with accompanying drawing.Voltage on the R5 becomes with current of electric and compares with the SCR trigger voltage.When increasing to motor, current of electric allows more than the minimum overcurrent value; when making voltage on the R5 greater than the SCR trigger voltage; the SCR conducting is with the time-delay relay power connection, when the voltage on the C1 is charged to 2/3 * 12V=8V; the level of NE555 the 3rd end is by high step-down; the relay J action, normally closed contact J1 disconnects, and realizes the over current of motor protection; and normal opened contact is connected, and realizes the time-delay relay self-locking.R2C1 has determined the overload in the certain limit that motor allows.To different motors, can suitably adjust R2 on request to change delay time.

The utility model has the advantages that than existing bimetallic overcurrent temperature relay any one protection operating point (R5) is set easily and exactly, operating point accurately, be swift in motion; Supporting easily with all kinds of low-power machines, making is simple, production cost is low, volume is small and exquisite.

Claims

1, the single-phase motor protecter of a kind of small-power; form by current sampling testing circuit, time delay relay circuit, overcurrent protection executive circuit and power supply; it is characterized in that the current sampling testing circuit is by current-limiting resistance R3; sample resistance R5 and controllable silicon SCR are formed, and the satisfied R5=SCR trigger voltage/motor that concerns that is provided with of R5 allows the minimum flow valuve of crossing.

2, the single-phase motor protecter of small-power according to claim 1; its feature also be time delay relay circuit by resistance R 2, capacitor C 1, the time base integrated package NE555 and relay J form; R2C1 determines delay time, and the working power of time-delay relay is controlled by controllable silicon SCR.