Several problems should be paid attention to the selection of PC grade dual power supply
Published:2013-10-25 Publisher:Langming Electrical (Popularity: )
At present, China"s market of PC double power supply according to the category of use (control load capacity) is mainly divided into the following two types
A, use category choice
1, at present, China"s market of PC double power supply according to the category of use (control load capacity) is mainly divided into the following two types:
A.AC-33B: application of motor mixed load. Not only includes motor, resistance load and 30% load following the incandescent lamp, making and breaking current of 6Ie, COSj=0.5;
B.AC-31B: application of no sense or micro inductance load, making and breaking current of 1.5Ie, COSj=0.8;
Due to the dual power supply is difficult to pass through the AC-33B test. Therefore, switch using demands to reduce some manufacturing factory, select AC-31B use category. Obviously, the double power source selection of double power supply using AC-33B than the alternative of using AC-31B is more safe and reliable.
Two, short circuit protection apparatus selection
PC dual power supply is different from the traditional CB grade dual power supply, the product does not have the function of short circuit protection, therefore, need to match short circuit protection apparatus in the periphery. Short circuit protection apparatus is generally divided into the fuses and circuit breakers. Fuse current limiting performance is good, limiting the short-circuit current is strong, commonly used in the system of local expected large short-circuit current; circuit breaker current limiting and rated conditional short-circuit current capacity is relatively poor.
In the choice of short-circuit protective device rated current value, the general principle is short-circuit protective device (fuse or circuit breaker) and the protected electrical appliances (dual power) rated current value consistent (1:1).
Select three, two segment and three segment type
The two section type double power supply is divided into two working position, namely "power" and "standby power supply, load will not appear" zero position, high reliability, fast conversion time.
The three section type double power supply is divided into three working position, products in addition to "common power" and "standby power", has a plurality of "zero", namely the main contact in neutral.
Note: the three section type double power supply for the middle of a plurality of "zero", power off time is relatively long, is 2-3 times the two section type power-off time. The three section type double power supply "zero" is mainly used for double power supply with high inductance or in large motor load conversion, do "transient stay" used to avoid the impact of current; and not for load during maintenance isolation in. During maintenance, still need to use isolation switch.
Four, action time selection
The measure of a double power supply switching speed of 5 kinds of action time (see GB/T14048.11). Double power supply shall be provided at least one action time to the user, is convenient for the user to choose according to use requirements.
Five, the contact switching time
Determination of disconnect the power up to second groups from the first group of main contact main contact is closed until the time of standby power supply.
Six, conversion time
Determination of from the main power supply is monitored deviation moment to the main contact closing standby power until the time (including the mechanism of action of time), including specially introduce delay (controller).
Seven, return of time
From the common power completely normalized moment to a group of main contact closing power instantaneous time plus specially introduce delay.
Eight, the total movement time
And the delay of the conversion time and controller of double power supply.
Nine, the off time
Conversion was measured from each phase arc eventually extinguished instantaneously to the main contact closing another power until the process time, including specially introduce delay. General users should pay attention to the "total movement time" or "conversion action time, to satisfy different use requirements of distribution system. The two section type PC double power supply and the total movement time is generally in the 50 ~ 300ms; the three section type PC double power supply and the total movement time is generally in the 350 ~ 600ms; class CB ATSE total movement time is generally in the 2000 ~ 3000ms;
Ten, to the high inductive load switching should pay attention to the problem of control
Double power supply in general is not allowed to bring large motor or high inductive load switching. For example, large motor load, when the switch in the operation and the power phase and the gap is large, it will be subjected to great mechanical stress impact, also produced by the motor back EMF induced current will cause the fuse or circuit breaker tripping. To solve the method used to absorb or reduce load resistance, or automatic transfer switch to delay conversion type, two groups of moving contacts before conversion adds a delay, can avoid the impact caused by the switching current in large motor or transformer load time.
