OEM Panels

VFD Variable Frequency Drive and Centrifugal Pump

Bob Lambert — Wed, 07 Mar 2018 11:59:35 +0000

VFD Variable Frequency Drive When a VFD Variable Frequency Drive is being selected for a specific motor application the first question is “Is it a Variable Torque or a Constant Torque application ?” The short answer is VARIABLE TORQUE = All Centrifugal Pump and Fan motor applications CONSTANT TORQUE = All other motor applications Centrifugal Pump operation A centrifugal pump and centrifugal fan operate using one principle. They move fluid by creating differential pressure between their inlet and outlet with a spinning impeller. Fluid is drawn into the center (eye) of the impeller and pushed toward the outlet by the differential pressure created when the impeller spins. Affinity laws define how a centrifugal pump or fan performs from 0-100% speed. They calculate Flow, Pressure and Horsepower at various points on a centrifugal pump curve and a centrifugal fan curve. It’s tough trying to understand centrifugal pump or centrifugal fan curves, but Affinity Laws are simple. If you were looking to learn more about pumps go to Intro to Pumps Affinity Laws apply to every centrifugal pump and every centrifugal fan. The laws are simple, but difficult to visualize. They are as follows. When a fixed impeller is spinning at 0-100% Motor Speed, Flow is proportional to Speed, Pressure is the Square of the Speed, and Power is the Cube of the Speed. Below is a table defining them using formulas Affinity Laws MOTOR SPEED (X) VARIABLE (Y) FUNCTION TYPE FUNCTION FORMULA 0-100% FLOW LINEAR (y=x) 0-100% PRESSURE SQUARE (y=x2) 0-100% HORSEPOWER CUBE (y=x3) It’s difficult to visualize formulas so let’s look at the curves generated by them. When you see all three curves together the laws become clear and you see something unexpected. When motor speed is reduced, power is reduced faster than flow, so it takes less power per unit flow. The reduced power per unit of flow becomes energy savings when a Variable Frequency Drive (VFD) is used to reduce motor speed. This becomes significant as the motor size increases. Centrifugal pump performance example The chart belows shows at 80% motor speed, centrifugal pump flow is 80%, but the power is 52%. AS DESIGNED – When sizing pumps and fans Engineers typically oversize them by >20% for various reasons. AS REQUIRED – Users typically only need <80% of designed centrifugal pump or fan flow capacity SAVINGS – Users can reduce their energy cost by 35% (1-.52/.80) by reducing motor speed / flow to 80%

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480V 3 Phase US industrial power

Bob Lambert — Tue, 05 Dec 2017 02:36:04 +0000

480V 3 Phase is the most common power system used in US industrial plants. American National Standards Institute (ANSI) classifies 208V, 240V and 480V 3 Phase power as low voltage power systems. Other ANSI voltage classifications are Medium, High, Extra High, and Ultra High Voltage that goes up to 1,100,000V. When you’re used to working with 120V or 240V it sounds wrong to call 480V low voltage, but there it is. You won’t see or even know that higher ANSI voltage classifications exist unless you work in electrical power distribution or in a very large industrial facility that requires more than 4 Mega Watts. Most US industrial facilities use 480V 3 Phase instead of 208V or 240V because it provides 2.3 (480 /208) times or 2.0 (480 /240) times more power with the same current. More important is it provides the same power with less current which provides added benefits. Reduced construction costs with smaller electrical service, wiring, conduits, and electrical devices. Reduced energy costs with less energy lost to heat in the form or current resistance. 480V 3 Phase Wye 480V 3 Phase Wye is like 208V 3 Phase Wye in that they’re both 3 Phase 4 Wire power configurations that include a neutral wire. Most 480V power systems are a Wye configuration because Phase to neutral voltage is 277V or below 300V It can power 277V single phase lighting loads A 480 3 Phase Wye power system is called 480V 3 Phase 4 Wire and 480Y/277V. These are technically more accurate because they refer to the neutral. The “4 Wire” in 480V 3 Phase 4 Wire refers to the neutral as 4th wire. The” Y” in 480Y/277V refers to the neutral as the center of the Y shaped power source. 480V 3 Phase Delta 480V 3 Phase Delta is a 3 Wire power configuration and does not include a neutral wire. Most 480V power systems are not a Delta configuration because the phase to ground voltage is 480V or above 300V. I’m always surprised when an industrial facility uses a 480 3 Phase Delta power system. Most of the time they are older industrial facilities so it must be related to when the facility was built.

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3 Phase Power vs Single Phase Power

automation — Sat, 27 Aug 2016 11:28:49 +0000

How does Electrical Power work? If you’re not electrically minded, think of 3 Phase vs Single Phase electric power as something easier to visualize like mechanical power. They’re very different, but both deliver power using pressure (force) and flow (speed). In both the power delivered is calculated by multiplying pressure (force) times flow (speed). In mechanical power, many terms describe the pressure or force (Foot Pounds, Pounds per Square Inch, etc.) and many terms describe the speed or flow (Rotating Speed, Gallons per Minute, etc.). In electric power, one term describes the pressure or force (Voltage) and two terms describe the speed or flow (Current and Amperes). In the earliest days Direct Current (DC), where the power flows in one direction like a water hose, was the standard for delivering electrical power. Now Alternating Current (AC), where the power flow is constantly alternating direction, is the standard for delivering electrical power. The standard for delivering electrical power changed from Direct Current (DC) to Alternating Current (AC) because Alternating Current (AC) delivers electrical power more efficiently over long distances. In the US, 60 Hertz (cycles per second) is the Alternating Current (AC) frequency. In some countries, 50 Hertz (cycles per second) is the Alternating Current (AC) frequency. What is 1 (Single) Phase Power ? If you’re not electrically minded, think of 1 (Single) phase power like a bicycle where only one leg (phase) is pushing on one pedal rotating around a crankshaft axis (neutral). Mechanically, power is calculated as leg pressure (Foot Pounds) times speed (Rotating Speed). Electrically, power is calculated as leg force (Voltage) times flow (Current). Single Phase power is a two wire Alternating Current (AC) power circuit. Most people use it every day because it’s the most common household power circuit and powers their lights, TV, etc. Typically there’s one power wire and one neutral wire and power flows between the power wire (through the load) and the neutral wire. In the US, 120V is the standard single phase voltage with one 120V power wire and one neutral wire. In some countries, 230V is the standard single phase voltage with one 230V power wire and one neutral wire. What is 2 (Dual / Split) Phase Power ? If you’re not electrically minded, think of 2 (Dual / Split) phase power like a bicycle where one leg (phase) can push on one pedal, or both legs (phases) can push on both pedals (180 degrees out of phase with one another) rotating around a crankshaft axis (neutral). Mechanically, power is calculated as leg pressure (Foot Pounds) times speed (Rotating Speed). Electrically, power is calculated as leg force (Voltage) times flow (Current). Dual Phase or Split Phase power is also Single Phase because it’s a two wire Alternating Current (AC ) power circuit. In the US, this is the standard household power arrangement with two (Phase A, Phase B) 120V power wires (180 degrees out of phase with one another) like two bicycle pedals and one neutral wire. This arrangement is used in most US households because of its flexibility. Low power loads (lights, TV, etc.) powered using either either of (2) 120V power circuits High power loads (Water Heaters, AC Compressors) powered using (1) 240V power circuit What is 3 (Three) Phase Power ? If you’re not electrically minded, think of 3 (Three) phase power like a three cylinder engine where three pistons (phases) located (120 degrees out of phase with one another) push rotating around a crankshaft axis (neutral). Mechanically, I’m not sure how to calculate the power. Electrically, power is calculated as cylinder force (Voltage) times flow (Current) times 1.732 (Square Root of 3). Three Phase power is a three wire Alternating Current (AC) power circuit. Most US commercial buildings use a 3 Phase 4 Wire 208Y/120V power arrangement because of its power density and flexibility. Compared to single phase, a 3 phase power arrangement provides 1.732 (the square root of 3) times more power with the same current and provides (7) power circuits. Low power loads (Lights, etc.) powered using any of (3) 120V single phase power power circuits Medium power loads (Water Heaters, etc.) powered using any of (3) 208V single phase power circuits High power loads (HVAC Systems, etc.) powered using (1) 208V three phase power circuit Most US industrial facilities use a 3 Phase 4 Wire 480Y/277V power arrangement because of its power density. Compared to 208V 3 Phase, 480V 3 Phase provides 2.3 (480 /208) times more power with the same current or 43% (208/480) less current with the same power. This yields additional benefits. Reduced construction costs with smaller electrical service, wiring, conduits, and electrical devices. Reduced energy costs will less energy lost as electrical current resistance (converted to heat).

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208V Single Phase and 208V 3 Phase

Bob Lambert — Tue, 19 Jul 2016 23:08:52 +0000

208V Single Phase and 208V 3 Phase power are easy to use, but hard to understand. If you want a simple understanding but aren’t electrically minded, start with a simple analogy you can build on. I like the bicycle analogy. Bicycle Analogy A tandem bicycle has two people providing power with four legs (pedals). Each leg (pedal) provides power (pedal pressure) at a unique angle (pedal angle) to the center (shaft). Look at the pedals. The four pedals (legs) are evenly spaced in a circle (360 degrees / 4 pedals = 90 degrees) around a center (pedal crankshaft). Electrical phases are commonly called legs. 3 Phase electric motors have 3 legs (phases) evenly spaced in a circle around the center (shaft) and they move in a circle around the center (shaft) like legs on a bike. 208V 3 Phase Power 208V 3 Phase power has 3 electrical legs (phases) evenly spaced in a circle (360 degrees / 3 phases = 120 degrees) around a center (neutral). Each leg (phase) provides power (phase voltage) at a unique angle (phase angle) to the center (neutral). 208V 3 Phase power also goes by the names 208V 3 Phase 4 Wire and 208Y/120V. These are technically more accurate because they refer to the neutral. The “4 Wire” in 208V 3 Phase 4 Wire refers to the neutral as 4th wire. The” Y” in 208Y/120V refers to the neutral as the center of the Y shaped power source. 208V 3 Phase Power Panel A 208V 3 Phase Power Panel provides 3 power circuit types (120V 1 Phase, 208V 1 Phase, 208V 3 Phase) in 7 circuit configurations based on Circuit Breaker (CB) Type (1 Pole, 2 Pole, 3 Pole) and Position (1, 2, 3, etc.) as shown below. Single Phase 120V – 1 Pole Circuit Breaker 120V 1 Phase (Phase A, Neutral) 120V 1 Phase (Phase B, Neutral) 120V 1 Phase (Phase C, Neutral) Single Phase 208V – 2 Pole Circuit Breaker 208V 1 Phase (Phase A, Phase B) 208V 1 Phase (Phase B, Phase C) 208V 1 Phase (Phase C, Phase A) Three Phase 208V- 3 Pole Circuit Breaker 208V 3 Phase (Phase A, Phase B, Phase C) Panel Directory (208 3 Phase 42 Circuit) explanation The (3) vertical lines are the three power phases (Phase A, Phase B, Phase C) The (21) horizontal lines are the power phase connections to the (42) circuit breaker positions The (18) dots are the (3) power phase to (42) circuit breaker position connections The (42) numbers are the (42) circuit breaker positions CB Type vs CB Position vs Power Connection Circuit Breaker Type Circuit Breaker Position 120V 1 Phase Connection 208V 1 Phase Connection 208V 3 Phase Connection 1 Pole 1, 2, 7, 8, 13, 14, 19, 20, 25, 26, 31, 32, 37, 38 Phase A and Neutral Not Applicable Not Applicable 1 Pole 3, 4, 9, 10, 15, 16, 21, 22, 27, 28, 33, 34, 39, 40 Phase B and Neutral Not Applicable Not Applicable 1 Pole 5, 6, 11, 12, 17, 18, 23, 24, 29, 30, 35, 36, 41, 42 Phase C and Neutral Not Applicable Not Applicable 2 Pole 1, 7, 13, 19, 25, 31, 37 Not Applicable Phase A and Phase B Not Applicable 2 Pole 3, 9, 15, 21, 27, 33, 39 Not Applicable Phase B and Phase C Not Applicable 2 Pole 5, 11, 17, 23, 29, 35, 41 Not Applicable Phase C and Phase A Not Applicable 3 Pole 1, 2, 7, 8, 13, 14, 19, 20, 25, 26, 31, 32, 37, 38 Not Applicable Not Applicable Phase A and Phase B and Phase C 208V 3 Phase Power Panel Wiring 120V Single Phase power wiring Install a 1 Pole Circuit Breaker (CB) Connect (1) 120V 1 Phase power wire to the 1 Pole CB Connect (1) Neutral wire to the Neutral Bar 208V Single Phase power wiring Install a 2 Pole Circuit Breaker (CB) Connect (2) 208V 1 Phase power wires to the 2 Pole CB 208V Three Phase power wiring Install a 3 Pole Circuit Breaker (CB) Connect (3) 208V 3 Phase power wires to the 3 Pole CB 208V 3 Phase Load balancing Ideally, the power circuit loads should be balanced across all three Power phases (Phase A, Phase B, Phase C). You can’t get it perfect, but it’s something to think about. Most Power Panels don’t have a documented load schedule. Below is an example of what one looks like.

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240V 3 Phase and 240V Single Phase

Bob Lambert — Sun, 26 Jun 2016 14:44:30 +0000

240V power is used in the US and parts of the world. In the US 120 / 240V 1 Phase 3 Wire is the standard for homes and 240V 3 Phase Open Delta is the standard for small buildings with large loads. In parts of the world 240V Single Phase 2 Wire is the standard for homes. Actual power company voltage varies (220v / 230v / 240v) by region, but to simplify we’re going to focus on 240V. 120 / 240V Single Phase 3 Wire (1P3W) In the US, 240V Power is provided to homes and small buildings as a 120/240V 1P3W power circuit. It provides 120V for light loads (lights, TV, etc.) and 240V for medium loads (Water Heaters, AC Compressors, etc.). MAXIMUM POWER – In a single phase power circuit maximum power is calculated as the voltage times the current. If we assume it’s a 200A power circuit then the maximum deliverable power is 200 x 240 as follows Current (Amps): 200A Voltage (Volts): 240V Maximum Single Phase Power 48 KVA Kilovolt Amps or 48 KW Kilowatts 240V 3 Phase Open Delta (3P4W) In the US, 240V Power is provided to small buildings with large loads as 240V 3 Phase Open Delta. It’s like 120 / 240V but also provides 240V 3 Phase for large loads (Machinery, etc.). It’s often called “Wild Leg” of “High Leg” Delta because one leg (Phase B) is different. THE GOOD – It’s inexpensive for the power company and it provides 120V / 240V Single Phase and 240V 3 Phase. THE BAD – The “Wild Leg” or “High Leg” (Phase B) can cause problems if you’re not aware it’s different. THE UGLY – The “Wild Leg” or “High Leg” (Phase B) is 208V to Neutral, so it’s different than the others. MAXIMUM POWER – In an Open Delta configuration power circuit the maximum power is a little more complicated because you have to calculate single and three phase separately. If we assume it’s a 200A power circuit then the maximum deliverable power is 200 x 240 calculated as follows. Current (Amps): 200A Voltage Volts): 240V Maximum Single Phase Power 48 KVA Kilovolt Amps or 48 KW Kilowatts Maximum 3 Phase Power = 1 Phase Power x 1.732 83 KVA Kilovolt Amps or 83 KW Kilowatts 240V Single Phase 2 Wire In some countries, 240V Power is provided to homes and small buildings as a 2 Wire 240V Single Phase power circuit. MAXIMUM POWER – In a single phase power circuit maximum power is calculated as the voltage times the current. If we assume it’s a 200A power circuit then the maximum deliverable power is 200 x 240 as follows. Current (Amps): 200A Voltage (Volts): 240V Maximum Single Phase Power 48 KVA Kilovolt Amps or 48 KW Kilowatts 415Y / 240V 3 Phase 4 Wire (3P4W) In some countries, 240V Power is provided to buildings with large loads as a 415Y/240V 3P4W power circuit. MAXIMUM POWER – In a Wye power circuit the maximum power is a little more complicated because you have to calculate single phase and three phase separately.If we assume it’s a 200A power circuit then the maximum power is calculated as follows. Current (Amps): 200A Voltage Volts): 240V Maximum 1 Phase Power per Phase = 200 x 240 48,000 Volt Amps (VA) per Phase or 48 Kilowatts (KW) per Phase. Maximum 3 Phase Power = 200 x 415 x 1.732 144 KVA Kilovolt Amps or 144 KW Kilowatts

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What Does UL508A, NEC, NEMA and IEC Mean?

automation — Mon, 30 May 2016 11:30:22 +0000

Like most industries the electrical industry uses many acronyms. The ones most commonly associated with electrical control panels are UL508A, NEC, NEMA, and IEC. These are acronyms for the safety standards used to produce and install electrical control panels and electrical wiring systems. What does UL508A stand for ? In the electrical world, UL stands for Underwriters Laboratories, an independent testing company that provides third party product safety standards and certification. UL508 is a UL safety standard for Industrial Control Panels. UL508A is a UL safety certification program that allows a panel shop to become a UL Listed Panel Shop. See UL508A Third Party Safety Approval for more detail. What does NEC stand for ? In the electrical world, NEC stands for the National Electrical Code. NEC is the safety standard used by most states, municipalities and cities. Building inspectors “the authority having jurisdiction” can reject an electrical installation, if the installation doesn’t follow the standards defined in the NEC. The National Electrical Code (NEC) is a standard by the National Fire Protection Association (NFPA) describing safe electrical installation methods. What does NEMA stand for ? in the electrical world, NEMA stands for National Electrical Manufacturers Association. NEMA is an association of US based electrical equipment manufacturers. NEMA produces electrical standards used by many US electrical manufacturers. What does IEC stand for ? In the electrical world, IEC stands for International Electrotechnical Commission, a worldwide organization that prepares and publishes International Standards for all electrical, electronic and related technologies.

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Electrical Control Panels for beginners

automation — Tue, 12 Apr 2016 11:30:39 +0000

Electrical control panels are designed and used to control mechanical equipment. Each one is designed for a specific equipment arrangement and includes devices that allow an operator to control specified equipment. Electrical panel components control every piece of equipment in every industry. It’s difficult to describe all possible combinations because every industry and most companies have defined component preferences. If you need to come up to speed on control panels fast, take your time. Find someone to help you, someone who knows what you’re trying to do. Start with the basics and build from there. Below are the basics.

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Electrical Power Components for beginners

automation — Sat, 12 Mar 2016 11:26:46 +0000

Electrical panel components are electrical power components when they’re used in electrical power circuits that power physical devices like Lighting, Heaters, Motors, etc. In the US, electrical power circuit wiring must follow the National Electric Code (NEC), a standard by the National Fire Protection Association (NFPA) describing safe electrical installation methods. The NEC requires every electrical power circuit to include a disconnecting means and circuit overload protection. The disconnecting means can be a switch, but it’s often a Circuit Breaker or Fused Disconnect because they also provide circuit overload protection. In a motor power circuit, the NEC also requires motor overload protection. Circuit overload protection prevents the wires from overheating and starting a fire. Motor overload protection prevents the motor from overheating and starting a fire. What is a Circuit Breaker ? A circuit breaker is a manually operated electrical power switch that can also detect short circuit and / or overload conditions. The most common type is Thermal Magnetic. It detects short circuit conditions magnetically and overload conditions thermally. When either condition is detected it breaks the circuit by turning itself Off. The advantage of using a circuit breaker, compared to a fused disconnect, is a circuit breaker doesn’t destroy itself breaking the circuit. After you correct the problem that caused the circuit breaker to trip or turn itself Off, you can just turn it back On. What is a Fused Disconnect ? A Fused Disconnect is the combination of a manually operated electrical power switch and a fuse. A fuse is a thin metal wire in a sand packed paper wrapper. It breaks the flow of electrical power a when short circuit or overload causes the metal wire to literally burn up. A fuse breaks the flow of electrical power by graceful self destruction. The disadvantage of using a fused disconnect for circuit protection, compared to a circuit breaker, is a fuse destroys itself breaking the circuit. After you correct the problem that caused the fuse to burn itself up or turn Off the power, you have to replace the fuse. What is a Motor Starter ? A Motor Starter is a device or combination of devices used to power and control a motor. At a minimum, a motor starter includes the following power safety devices. In addition, a Motor Starter generally includes another device (Contactor, Soft Start, Variable Frequency Drive, etc.) to control the motor. Disconnecting Means – a method of manually disconnecting power. Circuit Overload Protection – automatic power disconnect when an overload condition exists to prevent the wiring from getting hot and starting a fire. Motor Overload Protection – automatic power disconnect when an overload condition exists to prevent the motor from getting hot and starting a fire. What is an FVNR Starter ? A Full Voltage Non Reversing (FVNR) Starter is a 3 Phase motor controller with one motor contactor. An Across the Line (ATL) Starter means the same thing as an FVNR Starter. The contactor opens and closes the power circuit to turn the motor on and off. Full Voltage – the contactor simply opens and closes the motor power circuit. Non Reversing – the motor can’t be reversed using one motor contactor. What is an FVR Starter ? A Full Voltage Reversing (FVR) Starter is a 3 Phase motor controller with two motor contactors. Instead of using one contactor to open and close the power circuit to turn the motor on and off, it uses a forward and reversing contactor to control motor direction. The direction of a 3 Phase Motor is controlled by reversing (swapping) the connection of any two of the three phases. Full Voltage – the contactors simply open and close the motor power circuit. Reversing – the motor can be reversed using forward and reverse motor contactors. What is a Soft Starter ? A Soft Starter is a 3 Phase motor controller with a simple solid state power controller. Instead of simply opening and closing the power circuit like a motor contactor, it ramps the motor voltage up or down to turn the motor on and off more smoothly to eliminate electrical surges and mechanical shock. Soft Start – Ramps the motor voltage up to turn the motor on smoothly Soft Stop – Ramps the motor voltage down to turn the motor off smoothly A Soft Starter is more expensive than a motor contactor, but provides the added benefit of reducing electrical and mechanical shocks associated with starting and stopping a motor. What is a Variable Frequency Drive (VFD) ? A Variable Frequency Drive (VFD) is a 3 Phase motor controller with an advanced solid state power controller. Instead of simply ramping the motor voltage up or down like a soft start to turn the motor on and off, a Variable Frequency Drive (VFD) allows motor speed to be controlled at all times while running. A Variable Frequency Drive (VFD) is more expensive than a Soft Start (SS), but provides the added benefit of controlling motor speed. See Best Electrical Power Components for our recommendations

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Electrical Control Components for beginners

automation — Fri, 12 Feb 2016 11:21:50 +0000

Electrical panel components that are logical control devices are electrical control components. They’re used to control the sequence of events that define how a control panel functions. Some are manually actuated like a light switch and easy to understand. Let’s focus on electrically actuated control components. In their simplest form electrical control panel components are single components (relays, timers) that perform a single logic function. In their advanced form electrical control panel components are component packages (PLC) that perform many logic functions. What is a Control Relay (CR)? A control relay is the simplest electrically actuated control component. The simplest type is a Normally Open 1 Pole Single Throw (1PST) control relay. It’s like a light switch you use to turn a light on and off. The difference is you actuate the switch manually and a control relay actuates the switch electrically. At a minimum a control relay has an electrical operating coil, a spring, a stationary electrical contact, and a movable electrical contact that operate as follows. OFF – When the coil is de-energized the spring keeps the movable contact away from the stationary contact to open the switch. ON – When the coil is energized, the coil’s magnetic field draws the movable contact to the stationary contact to close the switch. Control relays typically have 1 to 4 sets of contacts (1 to 4 pole). The number of poles defines how many independent electrical circuits the relay can control. Each pole typically has three switch contact connections (Common, Normally Open, Normally Closed). Normal describes the switch contact’s connection to common when the coil is in its normal state or de-energized. Control relays can be ordered with some useful options. The value of these options are most evident during Quality Control testing, field start-up and troubleshooting. Coil (Energized) Indicator – to visually confirm when the coil is energized Contact (State) Indicator – to visually confirm when contacts are in energized state Manual (Button) Actuator – to move contacts to energized state (momentarily) Manual (Lever) Actuator – to move contacts to energized state (maintained) What is a Timing Relay (TR) ? A Timing Relay is the next simplest electrically actuated control component. They are control relays with built-in timers to control when their contacts change state. Timing relays turn other devices on and off at specific times. The most common timing functions are. ON TIMER: Controls when its contacts change state after its coil is energized. OFF TIMER: Controls when its contacts change state after its coil is de-energized. INTERVAL ON (ONE SHOT) TIMER: Controls how long its contacts remain in the energized state after its coil is energized. REPEAT CYCLE (SYNCHRONOUS / FLASHER) TIMER: Controls how long its contacts remain in the energized and de-energized state after its coil is energized (energized X seconds, de-energized X seconds, repeat). REPEAT CYCLE (ASYNCHRONOUS) TIMER: Controls how long its contacts remain in the energized and de-energized states when its coil is energized (energized X seconds, de-energized Y seconds, repeat). What is a Programmable Logic Controller (PLC) ? A Programmable Logic Controller (PLC) is a collection of electrical control panel components (relays, timers, etc.) in one package that can be programmed. PLCs are packaged in various forms and can range in price from under $100 to several thousand dollars. There are potential advantages and disadvantages to using a PLC compared to using a collection of individual electrical control panel components Potential Advantages User Appeal – A PLC can make customers like your equipment package more Material Cost – A PLC can be less expensive than multiple control components Physical Size – A PLC can be smaller than many control components Flexibility – A PLC can be easier to reprogram than rewiring several control components. Potential DisAdvantages User Appeal – A PLC can make customers like your equipment package less Material Cost – A PLC can be more expensive than individual control components Tools Cost – A PLC requires programming tools (computer, software, cables, etc.). Skills Cost – A PLC requires training to program the PLC to function as desired. See Best Electrical Control Components for our recommendations.

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NEMA Enclosure Ratings for beginners

automation — Thu, 28 Jan 2016 11:32:45 +0000

NEMA Enclosure ratings define where an enclosure was designed to be used and the level of protection it was designed to provide. In the electrical world, NEMA stands for National Electrical Manufacturers Association, an association of US based equipment manufacturers that produce standards used by many equipment manufacturers. Below is our NEMA Enclosure ratings list for beginners. See Best NEMA Enclosures for our manufacturer recommendations. NEMA Enclosure Ratings for beginners Enclosure Rating Popularity Definition NEMA Type 1 Popular General-purpose. Protects against dust, light, and indirect splashing but is not dust-tight; primarily prevents contact with live parts; used indoors and under normal atmospheric conditions. NEMA Type 3R Popular Intended for outdoor use. Provides a degree of protection against falling rain and ice formation. Meets rod entry, rain, external icing, and rust-resistance design tests. NEMA Type 4, 4X Popular Watertight (weatherproof). Must exclude at least 65 GPM of water from 1-in. nozzle delivered from a distance not less than 10 ft for 5 min. Used outdoors on ship docks, in dairies, and in breweries. The 4X model has corrosion resistance. NEMA Type 7 Popular Hazardous. For indoor use in Class I, Groups A, B, C, and D environments as defined in the NEC. NEMA Type 12 Popular General-purpose. Intended for indoor use, provides some protection against dust, falling dirt, and dripping noncorrosive liquids. Meets drip, dust, and rust resistance tests. Entire list of NEMA Enclosure Ratings Enclosure Rating Popularity Definition NEMA Type 1 Popular General-purpose. Protects against dust, light, and indirect splashing but is not dust-tight; primarily prevents contact with live parts; used indoors and under normal atmospheric conditions. NEMA Type 2 Rare Drip-tight. Similar to Type 1 but with addition of drip shields; used where condensation may be severe (as in cooling and laundry rooms). NEMA Type 3, 3S, 3X Rare Weather-resistant. Protects against weather hazards such as rain and sleet; used outdoors on ship docks, in construction work, and in tunnels and subways. 3X includes corrosions. NEMA Type 3R Popular Intended for outdoor use. Provides a degree of protection against falling rain and ice formation. Meets rod entry, rain, external icing, and rust-resistance design tests. NEMA Type 4, 4X Popular Watertight (weatherproof). Must exclude at least 65 GPM of water from 1-in. nozzle delivered from a distance not less than 10 ft for 5 min. Used outdoors on ship docks, in dairies, and in breweries. The 4X model has corrosion resistance. NEMA Type 5 Rare Dust-tight. Provided with gaskets or equivalent to exclude dust; used in steel mills and cement plants. NEMA Type 6, 6P Rare Submersible. Design depends on specified conditions of pressure and time; submersible in water or oil; used in quarries, mines, and manholes. NEMA Type 7 Popular Hazardous. For indoor use in Class I, Groups A, B, C, and D environments as defined in the NEC. NEMA Type 8 Rare Hazardous. For indoor and outdoor use in locations classified as Class I, Groups A, B, C, and D as defined in the NEC. NEMA Type 9 Rare Hazardous. For indoor and outdoor use in locations classified as Class II, Groups E, F, or G as defined in the NEC. NEMA Type 10 Rare MSHA. Meets the requirements of the Mine Safety and Health Administration, 30 CFR Part 18 (1978). NEMA Type 11 Rare General-purpose. Protects against the corrosive effects of liquids and gases. Meets drip and corrosion-resistance tests. NEMA Type 12, 12K Popular General-purpose. Intended for indoor use, provides some protection against dust, falling dirt, and dripping noncorrosive liquids. Meets drip, dust, and rust resistance tests. NEMA Type 13 Rare General-purpose. Primarily used to provide protection against dust, spraying of water and noncorrosive coolants. Meets oil exclusion and rust resistance design tests.

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