Rahshad Electric Co | رهشاد الکتریک

• Motor run capacitors

The rahshad made motor run capacitors are produced under the latest technology and according to the IEC 60252 international standard. The dielectric material of these capacitors is BOPP film in different um thicknesses and the associated electrodes are made of very thin metallic layers (less than 0.3 um) which will be metallized in a vacuum evaporation process. Any damage in dielectric will cause short circuits between the electrodes and high current will passes through and the created heat around the break point evaporates the metallic layer. After the break down, the short circuit disappears and capacitor continues working automatic ally. This process is called self – healing which occurs in less than 1/100 seconds. There will be no significant reduction in the capacitance as per the availability of the electrode and the evaporated part surfaces.

Technical specifications:
Nominal voltage (un)	400-450 and 500 vac (other on request)
Nominal frequency	50~ 60 HZ
Tolerance	aa5 % & aa10 % (other on request)
Working temperature	-25 c/+ 70 c & -25 c/ + 85c
Class of safety protection	Class A 30000 h Class B 10000 h Class C 3000 h Class D 1000 h
Dissipation factor (tg a)	Less than 20 bb104 at 50 HZ
Voltage test between terminals	2 un for 2 seconds
Voltage test between terminals and case	2 KVAC for 2 seconds
Max. permissible over voltage	1.1 un
Max. permissible over current	1.3 in
Casing	Flame retardant materials according to latest edition standard
Electrical connections	Wire, cable, single and double tag
Mechanical connections	M8 AL or pl stud, without stud, fast screw
Filler Material	Poly – ortan rezin
Compatibility with environment	Free from leakage materials and PCB free resin (Non – PCB)

The power rate shall not exceed 1.35 times of nominal power.

• Application

The most important application of these capacitors in starting up the single – phase inductive motors and small three – phase asynchronous motors with single – phase supply – capacitor installation causes phase displacement and create necessay magnetic rotating field in motors. It also provides relevant torque for motor running. It shall be noted that the imposed voltage on terminals is generally higher than supply voltage in single – phase motors equipped with motor run capacitors, the capacitor is connected in series with auxiliary winding to avoid the overload on auxiliary winding, the capacitance must not be high. Operating torque in these motors are generally between 50 ~ 70% of the no mind torque. Motor productivity is 90% of the similar three – phase motors and power is always dose to one so there is no need for power factor correction. These capacitors shall be caable of bearing the overload, low losses and good thermal stability. In practice, it’s sometimes necessary to start up an asynchronousthree – phase supply small three – phase asynchronous motors (with power less than 1.5 kw) can be connected to a single – phase power supply with a capacitor (as shown in figure). To reverse the direction, the capacitor shall be interchanged on motor phase. The achieved power is 70 ~ 80% of the rated three – phase power and the relevant torque is 25~ 30% of the rated one. Required rahshad capacitor isusually calculated by following formula.

•70 uf/kw for 220 v motors.

•22 uf/kw for 380 v motors.