There are a number of issues to using AC and DC together in the same electrical system. Briefly, they are: circuit boxes and hardware, outlets, wiring schemes and sizes, and switches. Circuit boxes The Electrical Code prohibits AC and DC in the same box. You’ll need two distribution boxes – one for AC and one for DC. Circuit breakers rated for …
Types of Residual Current Devices (RCD)
For domestic applications only the first five of the below listed residual current devices (RCD) need to be considered. For industrial and commercial buildings all of the classifications need to be considered. Table below aims to identify where each type of RCD can be used, together with the benefits provided. However, before looking at Table 2 there …
Time relays setting ranges explained by SIEMENS
Time relays are used in control switching operations involving time delay. Most of these time relays have multiple time setting ranges and most of them are explained below: Time Delay Definition Time relays perform either on-delay or off-delay timing. An arrow is used to denote the function of the timer. An arrow pointing up indicates …
Measurement of insulation resistance (IR) – Part 2
Continued from first part: Measurement of insulation resistance (IR) – Part 1 1. IR Values For Electrical Apparatus & Systems (PEARL Standard / NETA MTS-1997 Table 10.1) Max.Voltage Rating Of Equipment Megger Size Min.IR Value 250 Volts 500 Volts 25 MΩ 600 Volts 1,000 Volts 100 MΩ 5 KV 2,500 Volts 1,000 MΩ 8 KV 2,500 …
Measurement of insulation resistance (IR) – Part 1
Introduction The measurement of insulation resistance is a common routine test performed on all types of electrical wires and cables. As a production test, this test is often used as a customer acceptance test, with minimum insulation resistance per unit length often specified by the customer. The results obtained from IR Test are not intended …
Overview Of Electrical Loads In Building
The electrical design professional should determine a building’s electrical load characteristics early in the preliminary design stage of the building to select the proper power distribution system and equipment having adequate power capacity with proper voltage levels, and sufficient space and ventilation to maintain proper ambients. Once the power system is determined, it is often …
Light Emission Depreciation
Illuminance provided initially by a lighting installation will decrease in a gradual way during its use due to a reduction in lamp lumens, to lamps which burn down, and to accumulation of dirtiness in lamps, luminaires and surfaces of the room. However, it is possible to maintain illuminance at or above the minimum permitted value …
Direct On Line (DOL) Motor Starter
Different starting methods are employed for starting induction motors because Induction Motor draws more starting current during starting. To prevent damage to the windings due to the high starting current flow, we employ different types of starters. The simplest form of motor starter for the induction motor is the Direct On Line starter. The Direct …
What is the best transformer coolant?
One of the main sources of losses and reasons for temperature rise in various parts of a transformer are the magnetic circuit and windings. So what are the actually reasons of heating the transformer? Responsible for heat generation within the transformer are core loss, copper loss in windings (I2R loss), stray loss in windings and …
Analog Data Acquisition with Transducers
Transducers measure power system parameters by sampling instrument transformer secondaries. They provide a scaled, low-energy signal that represents a power system quantity that the SA interface controller can easily accept. Transducers also isolate and buffer the SA interface controller from the power system and substation environments. Transducer outputs are dc voltages or currents in the …
