SPOC Automation and BECI- who are we? • Pump Focused VFD company • Specialists in Optimizing Pump Control • SPOC 15+ Years in business • BECI 16+ Years in business • Both Family Owned • SPOC Based in Trussville, AL • BECI – Based in Conway, AR
Efficiency using Automation VFDs • “Power” Basics • AC Motor Basics • AFD Basics • Energy Savings Basics • Discrete Automation Advantages
The Basics HP is the measurement of the work that the motor can perform. 33,000 ft/lbs per minute or 746 Watts 1 HP = Note: 5250 comes from (33,000 ft·lbf/min)/(2π rad/rev)
The Basics Torque is: • directly proportional to HP • indirectly proportional to speed • related to current demand – so, the higher the torque, the higher the HP – the higher the current demand. To understand Horsepower and Torque better, we need to understand how a motor works……..
AC Motor Basics
The Basics Electric motors convert electrical energy to mechanical energy
The Basics The motor stator is made up of a series of windings wound to create a series of magnetic poles when energized
The Basics When 3 phase AC power is applied to the stator winding a rotating magnetic field is created.
The Basics Induction causes Rotor rotation The rotor tries to align itself with the rotating magnetic field. With no losses, the rotor would rotate at the synchronous speed.
The Basics An induction motor is basically a constant speed device because the stator field rotates based on the frequency of the AC power system Looking at the equation differently: what would happen to the speed of the AC Motor if the frequency to the stator changed?
The Basics The Basics 300 10 Hz 900 30 Hz 1800 60 Hz
VARIABLE FREQUENCY DRIVES How does a Variable Frequency Drive Work? THREE SECTIONS 1. CONVERTER - Transforms (Converts) AC Line Power to DC Voltage 2. DC FILTER - The DC Voltage is Cleaned 3. INVERTER - Tranforms (Inverts) the DC Voltage to Synthetic AC Voltage
DRIVE TERMS Pulse Width Modulation (output) Definition - DC current is switched on and off quickly to appoximate an AC sine wave
Energy Savings Basics
Energy savings • 50HP Motor running full speed for a year…How much does it cost to run? • @ 10 Cents per kwh, about $30k
Typical Variable Torque Loads • Most Pumps • Supply and Exhaust Fans • Aerators
This is THE $$$$ Equation!!! Variable Torque Application HP = K(Operating speed/nameplate speed)3 Max Volts 230/460/575 Variable Torque Constant HP V/Hz Ratio V/Hz Ratio Output Voltage V/Hz Ratio 0 Extended Frequency 60 Hz Frequency
Variable Torque Application HP = K(Operating speed/nameplate speed)3 • Why is this considered to be THE $$$$ Equation? Energy Savings! • HP equals cube of the speed, so • ½ speed = (1/2) x (1/2) x (1/2) = 1/8 HP • ¼ speed = 1/64 HP • A 100HP motor at ½ speed requires 12.5 HP • HP is directly proportional to $
Savings Example-oversized fan • If a zoo runs a 10HP Motor for 24 hours a day at full speed: • 10HP x (1)3 x 0.746 KW/HP = 7.46KW • 7.46KW x 24 hours = 179 KWhrs • If a zoo runs a 10HP motor for 24 hours a day at 3/4 speed: • 100HP x (3/4)3 x 0.746 KW/HP = 3.14 KW • 3.14 KW x 24 hours = 75.36 KWhrs • 58% Savings simply by slowing the fan down by 25%. • New Reduced airflow through fan is 75% of original
Savings Example-- • If a zoo runs a 100HP Pump for 12 hours a day at full speed: • 100HP x (1)3 x 0.746 KW/HP = 74.6KW • 74.6KW x 12 hours = 895 KWhrs • If a zoo runs a 100HP Pump for 24 hours a day at ½ speed: • 100HP x (1/2)3 x 0.746 KW/HP = 9.4 KW • 24 hour day: 9.4 KW x 24 hours = 225 KWhrs 75% energy savings to move the same amount of fluid
VFD “Myth Buster” #1 • Myth: VFD’s are rated VT and CT • Fact: VFD’s are rated based on over-current capabilites. Typically, drives are rated at • 110% overload for 1 minute, or • 150% overload for 1 minute.
AFD “Myth Buster” #2 • Myth: AFD’s are inefficient at low speeds. • Fact: The AFD is typically >96% efficient throughout the speed range. • The concern is the AC Motor: • It is self-cooled • The slower the motor is going, the less cooling from the fan • Most modern motors have specifications for what is allowed
AFD “Myth Buster” #3 • Myth: I’ll burn up motors if I connect more than one to an AFD • Fact: One of the biggest benefits of an AFD is that more than one motor can be controlled by one drive. All motors will receive the same voltage and frequency.
Automation VFD Basics
Pump Automation + VFD Controls
Pump Automation • Control process • Safety interlocks • Eliminate manual adjustments to hit targets • Variable Capacity • Flexibility for rate of flow or compression • Energy Savings +
Pump Automation Easy, right? …..but we forgot a couple things
Pump Automation + VFD startup technician PLC startup technician
Pump Automation PLC VFD Automation VFD PLC Technician SCADA
Typical Controls • Branch of Electrical Contractor • Usually 1 or 2 techs • Exists to support contractor business • Dedicated Controls Company • Typically small company • Can do anything approach • Customized solutions
Automation VFD ……..It’s In There • Simple Operation • Operator Friendly Startup • Standard Product • Standard Support
Automation Drives ……..It’s In There • Reduce Electrical Costs • Reduce On-off Cycles • Eliminate Bypass Valves • Simplified Startup • Single Vendor responsibility • Easy System Troubleshooting
Automation Drives • Typical savings $10-$15k installed cost advantage of traditional PLC based approach • Optimized for smaller systems with a few pumps or fans per system • Simple setpoint changes • Flow • Pressure • Temperature