Switches mains disconnect

Mains disconnect switch Fuses (internal and external)... 

Fixed power cords are common to machinery and household appliances, but care must be taken to ensure that the cord, strain relief, plug, and terminal block are type-approved and that the proper termination methods and makings are utilized. lEC-type terminal blocks (touch safe) are the preferred method for termination of the incoming power wiring. Other methods of termination are possible, such as for connection directly to circuit breakers, mains disconnect switch, PCBs and tabs/ screws on filters. Refer to the product standard for the alternative methods of input terminations. Solder connections shall not be the only method of fixing and in some cases are not allowed for high current connections. 

B. Mains Disconnect Switches Mains disconnect switches are required on all machines to isolate the entire electrical equipment. The OFF position must be lockable, lEC symbols for ON/OFF positions must be present and meet the relevant EU standards for construction and operation, which is assured if the device... 

Mains Disconnect Switches 116 Emergency Stop Switches 117 Fault-Tolerant Components and Safety Circuits 117 Transformers 118 Motors 118... 

As with the single bus arrangement, each connection is linked to the main bus through a circuit breaker, but the breaker may be bypassed using disconnect switches through a transfer bus and another breaker to the main bus. This permits isolation of the circuit breaker for maintenance without loss of service to the connection. 

Figure 2.128 describes the main components of a photovoltaic solar collector system that is connected to the grid. These include the AC service entrance, the AC and DC disconnect switches, the inverter, and the two kWh meters, one tracking the total solar production and the other tracking the electricity flow to (and from) the grid. 

Service entrance equipment should be installed in an indoor electrical room whenever possible. The equipment should include one to six main service entrance power circuit breakers or load break disconnect switches and feeder circuit breakers for loads within the plant. Circuit breakers and disconnect switches for 480/277 V systems that are rated at 1000 A or more must include groimd fault protection. Feeder circuit breakers will typically be molded case. Integrally fused circuit breakers are available with very high short circuit lAC ratings for both power and molded case circuit breakers. Fuses and current limiters for integrally fused circuit breakers must be stored within the electrical room. 

Fuses should not be used to protect secondary voltage feeders. The time current characteristics of fuses above 100 A will not coordinate with the groimd fault pickup currents and time delays of the main overcurrent protection (circuit breaker or fused disconnect switch) ground fault protection. A main load break disconnect switch can be equipped with current-limiting fuses to reduce the available short-circuit current from the utility and should have a three-phase voltage relay for single-phase protection. 

Two (2) to six (6) separate service entrance cables connected to the secondary side of one utility owned transformer can connect to separate main circuit breakers or main load brake fused disconnect switches that are mounted next to each other. The sum of the ampacity of all of the service entrance conductors must have a current rating equal to or greater than the present and future maximum demand for the plant. This approach can reduce the cost of the service entrance installation but will not provide the additional level of protection provided by having one main circuit breaker or one main fused disconnect switch. Therefore it is not as reliable. 

A hand-operated power disconnect device shall disconnect the whole equipment from main input supply power. There are several possibilities. A user-accessible disconnect switch located on the front of the product is preferred but not the only option. Some of the power disconnect methods are ... 

The caravan or motor caravan must be provided with a mains isolating switch and an RCD to break all live conductors (Regulations 721.411). An adjacent notice detailing how to connect and disconnect the supply safely must also be provided, as shown in Regulation 721.514. Electrical equipment must not be installed in fuel storage compartments (Regulation 721.528.3.5). Caravans flex when being towed, and therefore the installation must be wired in flexible or stranded conductors of at least 1.5 mm cross-section. The conductors must be supported on horizontal runs at least every 25 cm and the metalwork of the caravan and chassis must be bonded with 4.0 mm cable. 

Main distribution systems for water, steam, and electric power should be looped, with block valves (or disconnect switches on electric lines) at appropriate points so that, if any part of the system is damaged, supply can be obtained from another source. 

Some vertical drain lines in a building were no longer needed, so they were disconnected and capped but left connected to the horizontal main drain below. The caps were fixed with tape but were not made watertight as there was no way. it seemed, that water could get into them. Fifteen years later a choke developed in the main drain, water backed up into the disused legs and dripped into an electrical switch box. All power was lost, and some of the switch gear was damaged beyond repair [23]. 

Electrical fires First disconnect the apparatus or equipment by pulling the safety switch or switch off the mains to avoid possibility of being electrocuted. Then use Class C fire extinguisher. 

When the reaction is complete, remove the heat source and allow the apparatus to cool to room. temperature. Switch off the stirrer and disconnect from the mains and remove the condenser and addition funnel. Carefully lower the reaction flask about 40 mm (the stirrer paddle will be lifted from the bottom of the flask by 40mm), cut the copper wire or plastic tie holding the top of the stirrer rod in the rubber tube and carefully ease the stirrer rod out of the rubber connection. Unclamp the stirrer motor and put it aside. You can now remove the stirrer and. stirrer gland from the reaction flask, rinsing the. paddle into the flask with a little fresh solvent. ... 

A/C Disconnect- The main electrical ON-OFF switch near the A/C Condenser. 

The object of the test is to verify that the quality of the insulation is satisfactory and has not deteriorated or short-circuited. The test should be made at the consumer s unit with the mains switch off, all fuses in place and all switches closed. Neon lamps, capacitors and electronic circuits should be disconnected, since they will respectively glow, charge up and be damaged by the test. 

If one cell parameter (voltage, current, temperature) exceeds the allowable range, the unit will either open immediately the main switch or issue a warning command and allow for a short-time overload before disconnecting completely. The main power contactors have to be rated for slightly higher currents than the nominal load and should be able to break a few times the short-circuit current. Otherwise the battery should additionally be protected by a fuse. 

Always turn off and disconnect electrical equipment Irom the power mains before opening the equipment cabinet for servicing or cahbration procedures. Do not rely on switches to disconnect power, as sometimes they are defective, and sometimes the switch has been miswired or mislabeled such that the off position is actually the on position. 

Equipment must be isolated from all electrical energy sources by opening and locking all main power supplies. If the main power supply cannot be locked out, a qualified electrician must physically disconnect the equipment from the power source. Lockouts of electrical equipment are to be made at the main power supply—the use of local switches may leave other portions of the equipment energized. Once the electrical lockout is complete, an attempt should be made to start the equipment locaUy to ensure it is properly isolated before the maintenance work starts (and then all switches should be returned to their off position and tagged Do Not Operate ). 

---