The voltage between the electrodes is directly proportional to the pH of the test solution. The proportionality constant depends on temperature, so a temperature sensor is also necessary.
An open drip proof or ODP motor is a type of motor that typically runs cooler and does not overheat. A benefit to having the motor totally enclosed is that it's protected from the outside environment, including dust, airborne contaminants, and many weather disturbances such as wind-driven rain.
To calculate the pH of an aqueous solution you need to know the concentration of the hydronium ion in moles per liter (molarity). The pH is then calculated using the expression: pH = - log [H3O+]. Example: What is the pOH of a solution that has a hydroxide ion concentration of 4.82 x 10-5 M?
A 'p' type motor is a motor specifically designed to support and accommodate the proper form of 'p' type protection, so it can safely operate in a given hazardous gas environment. Once these standards are met, EM can have the motor tested and certified by an Authorized Test Institution if desired by the customer.
Chart: pH ≡ mV
| pH Voltage |
|---|
| pH Alkalinity | Millivolts |
|---|
| 0 pH | + mV |
| 1 pH | +1342.86 mV |
| 2 pH | +285.71 mV |
Which DC motor has got maximum self-loading property? Explanation: A differentially compound DC motor, flux reduces so sharply at small increase in load at higher values of load. It is advisable that motor should not be used beyond some load value, as it may damage itself by self-loading.
Three major factors should be considered when determining if a motor is compatible with a VFD: the motor winding insulation, motor bearings and pump operating speed range.
It's all in the engine code (sometimes referred to as engine number) and vehicle identification number (VIN). You can find the VIN in the lower corner of your windshield on the driver's side. In the series of numbers and letters, the tenth from the left denotes the model year and the eighth is the engine code.
The
starting kVA required by a
motor starting at full voltage is determined from the nameplate on the
motor or from the manufacturer.
Locked rotor indicating code letters electrical motors.
| NEMA Code Letter | kVA/HP with locked rotor | Approximate Mid-Range Value |
|---|
| F | 5.0 - 5.59 | 5.3 |
| G | 5.6 - 6.29 | 5.9 |
When dividing the total volt-amperes by the total voltage in this problem, the locked-rotor current is 44.4A (15,980 ÷ 360 = 44.4).
A short time rating of an electric motor can be defined as the extrapolated overload rating of the motor which it can supply for the specified short time without getting overheated. Now a days the machines are being designed and manufactured for short duration having sufficient overload torque capability.
Motor is rated in kW since it specifies the capacity of the motor to drive its load. It is the active power (kW) that is of interest when a motor drives a load. The motor converts the active power that it draws from the mains into mechanical power that the load consumes/demands. Thus, a motor is rated in terms of kW.
Motor insulation systems that are rated for inverter use will be specified on the motor nameplate (or a sticker). These systems should have wire rated for a minimum of 1600 volt spikes, F or H class insulation, and will be processed with 100% sold resin in a vacuum pressure impregnation (VPI) system.
Motor Duty / Load Cycle. The term duty defines the load cycle to which the machine is subjected, including, if applicable, starting, electric braking, no-load, and rest de-energized periods, and including their durations and sequence in time.
- Frame Designation (FR) – this is typically a two or three digit number followed by one or more letters that identifies important mounting dimensions.
- Manufacturers Type (TYPE).
- Horsepower Output (kW).
- Time Rating or duty (DUTY).
- Max Ambient Temp.
- Insulation System Designation.
- Speed At Rated Load (RPM).
- Frequency (HZ).
RATED voltage is the voltage on the nameplate - the "design point" for maximum power throughput and safe thermal operation. OPERATING voltage is the actual voltage applied at the terminals to the electrical equipment. For example - a machine has a rated voltage of 4160 volts at 60 Hz.
rated output power: That power available at a specified output of a device under specified conditions of operation. (188) Note: Rated output power may be further described; e.g., maximum rated output power, average rated output power.
The nominal power in kW (Pn) of a motor indicates its rated equivalent mechanical power output.
Multiply the motor voltage by the full-load current. The result is in watts. Divide watts by 1,000 to give kilowatts. For example, 230 volts x 20 amps = 4,600 watts; 4,600 watts divided by 1000 = 4.6 kilowatts.
For an electric motor, efficiency is the ratio of mechanical power delivered by the motor (output) to the electrical power supplied to the motor (input). Thus, a motor that is 85 percent efficient converts 85 percent of the electrical energy input into mechanical energy.
A DC motor consists of an stator, an armature, a rotor and a commutator with brushes. Opposite polarity between the two magnetic fields inside the motor cause it to turn. DC motors are the simplest type of motor and are used in household appliances, such as electric razors, and in electric windows in cars.
The quickest method to closely estimate motor horsepower is to use a digital clamp meter to measure current and voltage to the motor, and then perform a simple calculation. Use this formula to estimate motor horsepower. Horsepower(hp)= Voltage x Amperage x % EFF x power factor x 1.73/746.
Use a strobe tachometer to determine motor RPM and then set up a generic motor in the database for that RPM. If loading cannot be provided by the operator use the acquired data and RPM to approximate loading. You can view the power factor for a value around 88 to 92 to approximate full load.
This data tells you at which voltage the motor is made to operate. Nameplate-defined parameters for the motor such as power factor, efficiency, torque and current are at rated voltage and frequency. When the motor is used at other voltages than the voltage indicated on the nameplate, its performance will be affected.
For motors less than ½ horsepower, the code letter on the nameplate represents the locked-rotor kVA. On larger motors, it identifies the locked-rotor kVA per horsepower. Generally, the farther a code letter is from A, the higher the inrush current per horsepower.
Service factor if other than 1.0. For motors equipped with thermal protectors, the words “thermally protected” if the motor provides all the protection described in MG 1-12.52. (See MG 1-1.71 and MG 1-1.72.) For motors rated above 1 hp equipped with over-temperature devices or systems, the words OVER TEMP.
Motor service factor (SF) is the percentage multiplier that a motor can handle for short periods of time when operating within its normal voltage and frequency tolerance. In other words, it is a fudge factor that give extra horsepower when it's occasionally needed. A SF is an operational margin.
Which power is mentioned on a name plate of a motor? Explanation: Name plate of the motor shows rated values i.e. rated speed, rated current, rated voltage. It also shows output power available at shaft when all other quantities are set to rated values.
The term “inverter-duty” refers to a motor whose speed is controlled by an inverter or VFD (variable frequency drive). While both inverter-duty motors and standard motors are capable of operating under VFDs, the main differences lie in construction and capability.
