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Quantity | Description
1 40-watt electric lamp
1 60-watt electric lamp
2 75-watt electric lamps
6 100-watt electric lamps
6 Normal base lamp sockets
10 Color-coded resistors with different values
3 0.5-kVA control transformers (two windings rated at 240 volts each and one winding rated at 120 volts)
1 7.5-µAC capacitor with a voltage rating not less than 240 VAC
1 10-µAC capacitor with a voltage rating not less than 240 VAC
1 25-µAC capacitor with a voltage rating not less than 240 VAC
1 9-lead dual-voltage three-phase motor (any horsepower)
1 Single-pole switch
2 3-way switches
1 4-way switch
Two-conductor romex wire (number of feet is determined by individual laboratory conditions)
Three-conductor romex wire (number of feet is determined by individual laboratory conditions)
1 Octagon metal box of PVC light fixture box
3 Metal or PVC switch boxes
Quantity | Description
1 Control transformer to step your laboratory line voltage down to 120 VAC 3 Three-phase motor starter that contains at least two normally open and one normally closed auxiliary contact 3 Three-phase contactors (no overload relays) containing one normally open and one normally closed auxiliary contact 3 Three-phase motors 1/3 to 1/4 hp or simulated motor loads (Note: Assuming a 208 volt, three-phase, 4-wire system, a simulated motor load can be con structed by connecting three lamp sockets to form a wye connection. These lamps will have a voltage drop of 120 volts each. If a 240 volt, three-phase system is in use, it may be necessary to connect two lamps in series for each phase. If two lamps are connected in series for each phase, these three sets of series lamps can then be connected wye or delta.)
1 Three-phase overload relay or three single-phase overload relays with the overload contacts connected in series
1 Reversing starter, or two three-phase contactors that contain one normally open and one normally closed contact, and one three-phase overload relay
4 Double-acting push buttons
6 3-way toggle switches to simulate float switches, limit switches, and so on
4 Electronic timers (Dayton model 6A855 recommended)
3 11-pin control relays (120 volt coil)
3 8-pin control relays (120 volt coil)
4 11-pin tube sockets 3 8-pin tube sockets
3 Pilot light indicators
1 Three-phase power supply (This laboratory manual assumes the use of a 208-volt, three-phase system. If an equivalent motor load is employed, the design may have to be modified to compensate for a higher voltage.)
Most of the parts listed can be obtained from Digikey, Mouser or Grainger Industrial Supply.
The Dayton model 6A855 timer is recommended because of its availability and price. Also, it's a multifunction timer and can be used as both an on- and off-delay device. It will also work as a one-shot timer and a pulse timer. Although the Dayton timer is recommended, any 11-pin electronic timer with the same pin configuration can be used. One such timer is available from Magnecraft (model TDR SRXP-120; www.magnecraft.com). This timer is also available from Mouser Electronics (www.mouser.com). Other electronic timers can be used, but if they have different pin configurations the wiring connections shown in the text will have to be modified to accommodate the different timer.
The 8- and 11-pin control relays and sockets can be purchased from Grainger, Mouser Electronics, or Newark Electronics (www.newark.com). The control transformer for use in the controls sections can be purchased from Mouser Electronics or Sola/Hevi-duty (www.solaheviduty.com). Model E250JN is recommended because it has primary taps of 208/240/277 volts. The secondary winding is 120/24. It is also recommended that any con trol transformer used be fuse protected. Another control transformer that can be used is available from Grainger. It is rated at 150 VA and has a 208 volt primary and 120 volt secondary. The 0.5 kVA control transformers are available from Grainger or Newark Electronics. Transformers rated at 0.5 kVA are used because they permit the circuit to be load heavy enough to permit the use of clamp-on-type ammeters.
Stackable banana plugs are available from both Grainger and Newark Electronics. The oil-filled capacitors listed are available from Grainger. Color-coded resistors can be obtained from Newark Electronics or Mouser Electronics.
Connection diagram for an 11-pin relay.
Connection diagram for an 8-pin relay.
Connection diagram for an 8-pin relay.
Dayton timer model 6A855. This timer mounts in an 11-pin tube socket and can be set to operate as a repeat timer, a one-shot timer, an interval timer, and an on-delay timer.
The thumb-wheel switch sets the time value.
Full range times can be set for 9.99 seconds to 999 minutes.
Three-phase contactor. This contactor con tains one normally open auxiliary contact and three load contacts. The contactor differs from the motor starter in that the contactor does not contain an overload relay.
Control relays. These relays contain auxiliary contacts only and are intended to be used as part of the control circuit. They are capable of controlling low-current loads such as solenoid valves, pilot lights, and the like.
Eight-pin on-delay timing relay. This timer can be used as an on-delay timer only. Time setting is adjusted by the knob on top of the timer.
One single-phase and one three-phase overload relay. The three-phase overload relay contains three heaters but only one set of normally closed auxiliary contacts. If an overload should occur on any of the three lines, the contacts will open.
Three-phase motor starter with two normally open and one normally closed set of auxiliary contacts. Notice that a motor starter contains an overload relay as part of the unit.
Light sockets mounted on a metal plate. The sockets have been connected to form a wye connection. This can be used to simulate a three-phase motor load.
Eight- and 11-pin tube sockets. All wiring is done to the socket and the relay is then plugged into the socket.
Pneumatic off-delay timer. A microswitch has been added to the bottom to supply instanta neous contacts for the timer.
Three push-button station. The bottom push button is normally closed. The two top buttons are double action. Each contains both a normally open and normally closed set of contacts.
Eight- and 11-pin control relays contain two sets of double-acting contacts. Eleven-pin relays contain three sets of double-acting contacts.