Discussion on the problems before the set of electrical isolation switch of double power supply
Published:2013-10-25 Publisher:Langming Electrical (Popularity: )
Double power supply automatic switch has two segments and three segments two, two section type double power switch main contact only two working position (main power and backup power bit), the three section type double power switch main contact have three work (main power, standby power and zero a). Through the above description, we know that the two section type double power structure because of its wireless broken bits (zero), line protection and repair required to set the isolation switch. The three section type double power supply consists of "zero", have the ability to break the current, so whether it can be used as electrical isolation?
Double power supply automatic switch has two segments and three segments two, two section type double power switch main contact only two working position (main power and backup power bit), the three section type double power switch main contact have three work (main power, standby power and zero a). Through the above description, we know that the two section type double power structure because of its wireless broken bits (zero), line protection and repair required to set the isolation switch. The three section type double power supply consists of "zero", have the ability to break the current, so whether it can be used as electrical isolation?
According to the "code for design of low voltage distribution of GB50054-95 standard"
Article 2.1.3 when the maintenance, testing and repair equipment necessary to disconnect the power supply when, should set the electrical isolation.
Article 2.1.6 the electrical isolation can adopt the following electrical appliance:
1 unipolar or multipolar isolating switch, isolating plug;
2 plug and socket;
The 3 connecting piece;
4 do not need special terminal demolition wire;
5 fuse.
"General electrical equipment distribution in" code for design of GB50055-93 standard
Article 2.5.1 the isolated electrical installation shall comply with the following provisions:
The main circuit of 1 each of the motor should be installed with electrical isolation, when meets the following conditions at the time, the number of motor can share a set of electrical isolation:
(1) a group of motor share a set of electrical short circuit protection;
(2) by the same distribution box (screen) power supply and allows a group of motor without selectively disconnect.
2 motor and its control appliances should share a set of electrical isolation. Meet the requirements of short circuit protection electrical isolation can be used as electrical isolation.
3 electrical isolation should be installed in the control electric appliance near or other convenient in operation and maintenance of the site. No load disconnecting the electrical isolation should be able to prevent the irrelevant personnel misoperation.
The current national standard "basic standard for low voltage apparatus", has low voltage air switch (switch), isolating switch, isolator, fuse switch, fuse isolator and other electrical isolation; low voltage circuit breaker standard also included isolation.
According to the above regulations and standards requirements, electrical switch front-end should set the electrical isolation automatic switching in distribution system. The three section type double power supply is arranged "the main effect of zero" is when the load is high inductance or motor load, do stay with in order to avoid the impact of transient current, rather than the load for maintenance isolation in. So with the three section type zero double power supply switch is not as electrical isolation, in order to meet the need for isolation repair problems, should also set the electrical isolation alone in front of double power supply switch.
