What is a string of outdoor lights suspended between two points?
A string of outdoor lights that is suspended between two points. A term commonly used to describe the stationary (Stator) member of a DC Motor….Electrical Definitions.
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Which of the following best describes festoon lighting?
Which of the following best describes festoon lighting? A string of outdoor lights that is suspended between two points Defined in NEC Article 100 — Definitions. What is the term used to describe an enclosing case constructed so that dust will not enter under specified test conditions?
What is Article 100 in the NEC?
Article 100 defines a Grounded Conductor as – A system or circuit conductor that is intentionally grounded. And that in spite of this, Grounding Conductors are not considered Grounded Conductors by the NEC.
Why do we need to connect the ground rod?
Ground rods, also known as grounding electrodes, are used to connect the grounding system of electrical systems to earth ground. Ground rods are very good conductors of electricity and allow any dangerous electricity to flow to ground, taking the danger away from you and the electrical panel.
What is the point on a wiring system called that takes current to supply utilization equipment?
Outlet. A point on the wiring system at which current is taken to supply utilization equipment. Overcurrent. Any current in excess of the rated current of equipment or the ampacity of a conductor.
What is an outlet where one or more receptacles are installed?
A RECEPTACLE OUTLET is where one or more receptacles are installed. receptacle outlet – an outlet where one or more receptacles are installed. outlet – a point on the wiring system at which current is taken to supply utilization commitment.
What type of branch circuit supplies two or more receptacles or outlets for lighting and appliances?
A general-purpose branch circuit supplies a number of outlets for lighting and appliances. This type of circuit supplies lights, receptacles, appliances, or any combination thereof. Of the four branch circuit types, this is the most common.
What is defined as the circuit conductors between the final overcurrent device protecting the circuit and the outlet S?
1. The conductors between the final overcurrent device and the outlet(s) are defined as branch circuit conductors. The size of the circuit breaker installed on a branch circuit, not the conductor size, determines the rating of the circuit.
Does a washing machine need to be on a separate circuit?
In the Laundry Room. Your laundry room should have a dedicated circuit of at least 20 amps. If you have a gas dryer, both your washing machine and gas dryer may be plugged into the same outlet. If you have an electric dryer, it will need its own dedicated 20-amp, 220-volt circuit.
Why relay is used in PLC?
Relays are used to isolate one voltage level from another. A relay is used to energize the starter, which, in turn, switches the motor voltage while the PLC controls the relay. Wired to provide a control sequence, relays may also be used for simple control schemes where a PLC would prove uneconomical.
Which relay is used for feeder?
Buchholz relay
What is the overcurrent relay?
An overcurrent relay is a type of protective relay which operates when the load current exceeds a pickup value. It is of two types: instantaneous over current (IOC) relay and definite time overcurrent (DTOC) relay. When the relay operates, one or more contacts will operate and energize to trip a circuit breaker.
Why MHO relay is called MHO relay?
The relay is called Mho relay because its characteristic is a straight line, when plotted on an admittance diagram (G-B axes i.e., conductance – susceptance axes) as in the figure.
What is an undervoltage relay?
A relay that has contacts that operate when the voltage drops below a set voltage. Undervoltage relays are used for protection against voltage drops, to detect short-circuit faults, etc.
Where is the plug setting multiplier?
Plug setting multiplier of relay is referred as ratio of fault current in the relay to its pick up current. Suppose we have connected on protection CT of ratio 200/1 A and current setting is 150%.
How do you calculate overcurrent settings?
Calculation of Over Current Relay Setting:
- Over Load Current (In) = Feeder Load Current X Relay setting = 384 X 125% =480 Amp.
- Required Over Load Relay Plug Setting= Over Load Current (In) / CT Primary Current.
- Required Over Load Relay Plug Setting = 480 / 600 = 0.8.
When the fault current is 2000 A for a relay setting of 50% with CT ratio 500 5 the plug setting multiplier will be?
Hence, the fault current in the secondary of the CT is 5 × ( 2000 / 400) = 25 Amps. Hence, the plug setting multiplier = 25 / 2.5 = 10. That means the fault current in the secondary of the CT is ten times greater than the operating current of relay coil.
What is PSM and TMS?
TSM is time setting multiplier which comes into role only when pick-up value is reached. Practically PSM tell us about the magnitude of fault. The more the value of fault current, the more will be the PSM and hence the relay should clear the fault more quickly.
Which relay is used for transformer protection?
The ETR-4000 is suitable for application on small, medium, and large two winding power transformers . Multiple current inputs are used to provide primary protection, control and back-up protection of transformers, including current differential, restricted ground differential, and overcurrent protection .
What is Pickup value?
The pickup point is the current or voltage at which the plunger or armature begins to move and, in a switchgear relay, the pickup value can be set very precisely. These relays are usually instantaneous in action, with no intentional time delay, closing as soon after pickup as the mechanical motion permits.
Which is called Rated burden of relay?
Burden of a protective relay is the power.
Why CT secondary is shorted?
Unless a burden (i.e. meters, relays, etc.) is connected to the CT, current transformers should always be shorted across the secondary terminals. The reason is very high voltages will be induced at the terminals.
What is knee point voltage?
The knee point is defined as the voltage at which a 10% increase in applied voltage increases the magnetizing current by 50%. For voltages greater than the knee point, the magnetizing current increases considerably even for small increments in voltage across the secondary terminals.
What is ISF CT?
For any CT, Instrument Security Factor(ISF) is nothing but the ratio of Maximum limited Primary current to rated Primary Current. Basically, the ISF is used to protect the load connected in the secondary side of the metering CT i.e meters etc.