Electrical engineering laboratory

[1]   Click to Enlarge TRANSFORMER Single phase double wound copper transformer having primary 230VAC and secondary 115V AC with a rated capacity of 1KVA. The primary and secondary terminals are brought out for conducting laboratory experiment with legend printed for convenience. This is assembled in a powder coated MS metal box. Specifications: Primary : 230 V AC Secondary with tappings at 86.6% and at 50% of primary voltage. Rated capacity: 1KVA Terminations: Separate 4mm Banana terminals at input and outputs Enclosure: Powder coated MS metal cabinet, with separate screw terminal for earth connection. See Enlarge Click to Enlarge PORTABLE VARIAC This is a variable auto transformer. This is also called as Dimmer-stat. This is used to vary the output voltage by rotating a knob placed above this instrument. The output voltage can be varied from 0 to 270V AC, when its input terminals are connected to 230V AC. It can deliver 6A of current at its peak rated voltage. The entire instrument is assembled in a sheet rolled powder coated MS metal box with separate screw terminal for earth connection. Specifications: Input: 230 V AC Output: Variable in the range of 0 to 270V AC. Rated capacity: 6A See Enlarge Click to Enlarge RHEOSTATS Rheostat is a variable resistance device. The function is similar to a potentiometer. These are specified by (a) the maximum resistance required for variation in your circuit, and (b) the current handling capability. This is available in different current ratings. The connections for the rheostat are securely terminated with three numbers of 4mm banana terminals. These terminals in turn can be used for making connections with your circuitry. The number of tubes and the gauge wires vary depending on the current handling capability. These are available as single tube and double tube rheostats. The rheostats are mounted on a strong powder coated metal base. Rheostats are available in different current ratings and resistance values. See Enlarge Click to Enlarge LOADING RHEOSTAT Loading rheostat is a high current rheostat. This is no different from that of a normal rheostat. The only difference is in current handling capabilities for the purpose of loading. The current is handled in discrete steps by using fuse-protected switches, in steps of 1A per step when operated at 250V DC. This is used for the purpose of loading an electrical circuit where high current rating is desired. The loading rheostat arrangement depends on the current handling capabilities. Loading rheostats are available for single phase and three phase circuit applications. See Enlarge Click to Enlarge LOADING INDUCTOR This is a single-phase choke coil loading inductor. This is required when experimenting to determine the output characteristics of devices like a transformer etc. For example, if you want to measure the effect of presence of an inductor, in a single-phase electrical circuit, then this loading inductor becomes a very useful accessory. Normally a loading rheostat (R), loading inductor (L) and loading capacitor (C) (popularly called as RLC loads) is associated in an electrical setup for the purpose of calculating efficiency of the circuit. This loading inductor is specially designed for experimenting in electrical laboratories. This is arranged in a core type structure. The air gap in the coil is adjustable by a gradually moving, screw wheel mechanism. The air gap so adjusted is proportional to change in the magnetic reluctance. These changes make a variation in the current from 20% to the rated current. In general the coil voltage is 230V AC. The outputs are terminated on Banana terminals, for easy interconnections. The entire structure is made of heavy 1” angle iron pillars duly fastened to the wooden base. These are variable in 230V AC, at 1 to 10 Ampere capacity and continuously adjustable. See Enlarge Click to Enlarge 3 POINT DC STARTER 3 point DC starter is a unit intended to limit the starting current in a DC circuit. This starter is a must for any DC motor applications. This starter has three functions. (a) To provide series resistance in a DC circuit when this starter is in START position. I.e. In STARTposition full resistance is included, and is reduced to zero ohms when the handle is moved to ON position, in discrete steps. The starter is held in ON position by an electromagnet. At this ON position the DC circuit gets its full current from the DC Rectifier unit. In the case of a DC motor, this is connected in series with the armature circuit, to limit the starting current and eventually this resistance is CUTOUT, from the circuit. There by enabling the motor to run at it’s full armature current. Therefore this starter acts as a first order protection circuit, in between a DC rectifier unit and the DC circuit. (b) No Volt Coil (NVC) – This is normally connected to Field circuit in a DC motor. In case of a failure in current in this circuit, for any reason, namely accidental tripping, or unintentional break in field circuit, this coil will provide a signal to the electromechanically held arm (handle) to release, and the starter is switched to OFF position, thereby providing safety to the system. (c) Over Load (OL) release switch – This is connected in series with the armature circuit. In case of current beyond the rated current of this coil in the circuit, this automatically trips the electromagnet, which is holding the handle in ON position. Thereby tripping the starter from being over loaded. See Enlarge [1] Go to Top