BENSHAW SOLID STATE STARTER PDF

Benshaw is pleased to offer Solid-State Starter training at our facilities in. Benshaw Product Downloads. Catalogs: Benshaw Product Catalog. Solid State Motor Control. Technology. Publication #:

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The soljd of motor starters comprises a group of switching elements which may be used to control electrical power to a load. As the name implies, motor starters are commonly used to supply electrical power to motors in industrial control environments.

Motor starters are also used to control elements other than motors, such as resistance heaters, lighting, and battery chargers. Prior art motor starters included mechanical devices which controlled the introduction of series resistance with AC motors.

By varying the resistance between the line and the load, a controlled application of power could be achieved to an AC motor. Stxrter solid state devices can replace such resistance type motor starters by using control gated semiconductor devices such as thyristors or SCR’s.

Benshaw Solid State Starter With Sep

Such semiconductor devices are used in series between the line and the load, or motor. Through the use of known gating circuits, such semiconductor devices can be used to control the power applied to a load, such as an AC motor circuit. Use of solid state devices has permitted present solid state motor starters to function without the need for external resistors. The benshxw starter can now be housed in a single enclosure or structure which in many applications it is desirable or necessary to have sealed from the working environment.

Unfortunately one of the characteristics of such semiconductor devices is their generation of heat.

Such heat can be carried away from the semiconductor devices through the use of heat sinks. The benshaq must then be conducted away from the heat sink and ultimately outside of the control enclosure. In environments where it is required to maintain a sealed or ventilation restricted enclosure, the behshaw size of the enclosure grows rapidly with the power rating of the semiconductor device.

One solution to reduce the heat generated in the semiconductor devices during normal operation of electrical equipment has been to wire and mount a separate bypass contactor in parallel with the semiconductor devices.

Such bypass contactor would normally be a three phase magnetically operated contactor wired in parallel to the semiconductor device. Soliv the semiconductor or SCR was fully gated on ztarter the applied AC voltage to the motor is at a maximum, the bypass contactor would be actuated, thereby providing a path around the semiconductor device for carrying the load current.

Mechanical contactors generating less heat than the semiconductor device can be used. The problems inherent with such separate bypass contactor in parallel to the semiconductor device have been that the contactor device itself requires a significant amount of space in which to be mounted and the electrical wiring required to provide such bypass circuit occupies additional enclosure space.

Regal Beloit | Benshaw

In the past use of a separate stand alone bypass contactor and its associated wiring to sloid a parallel path often resulted in only a limited reduction in the size of the enclosure required for a reduced voltage AC motor starter.

In addition benshw the bypass contactor, bneshaw motor starter applications also require an in-line contactor. This device acts as an electrically operable mechanical disconnect of the line from the load. Much like the bypass contactor, this separate in-line contactor required additional wiring from the incoming lugs and terminals to the contactor solif then from the in-line contactor to the semiconductor control device.

The interconnection wiring in the case of motor starting is significant because in normal industrial motor control applications, the wiring size required to handle full motor current conditions is quite large.

Such wiring is not only costly but difficult to install as its large diameter requires that soolid bend or solld in direction maintain a minimum bending radius so as not to damage the conductor. Therefore, any reduction in interconnection benshaa can result in a significant space saving in the respective motor control enclosures. It is an object of the present invention to reduce the heat generated in the control enclosure without the need for separate stand alone contactor devices and their associate interconnected wiring.

Another object of the invention is to provide a motor starter control that can be mounted in a motor enclosure significantly smaller than the prior art devices which required considerable interconnection wiring. The present invention provides for mounting the semiconductor devices between heat sinks which conduct the heat away from the semiconductor device and provide stzte current path to and from the semiconductor device.

In addition the benzhaw sink provides a means for mounting a stationary contact which is electrically and mechanically engageable with a movable contact to complete either an incoming current path or a bypass or shunting current path. In the case of the bypass current path, the heat sinks may have a stationary contact on both the incoming and outgoing heat sinks such as to provide a shunting current path between adjacent heat sinks and around the semiconductor. Such stationary dtarter are engaged by a movable contact bar.

  ASTM A262 PDF

This configuration removes the necessity for any interconnection wiring to a separate bypass contactor and the need for a separate stand alone bypass contactor device. A stationary contact mounted on the soid heat sink similarly provides for the incoming line contactor function without the necessity of wiring to a separate stand alone device.

This contactor assembly 1 includes two heat sinks 2a, 2b arranged in generally parallel relationship, having two semiconductor devices 3a, 3b physically and electrically joined to the heat sinks. The heat sinks 2a, 2b generally can be of the extruded aluminum type commonly used in semiconductor power assemblies and bus work.

The semiconductors 3a, 3b could be silicon thyristors which through gating circuits not shown can be controlled in their firing phase relationship to control the output voltage and current. Power is supplied to the assembly by incoming line connector or lug 10a. An electrically operated incoming solenoid 8 connects the line voltage received at lug 10a to the line heat sink 2a by means of a movable line contact 7 which connects respectively the stationary line contacts 6a to 6b.

Contact 6a is mounted directly upon the incoming line heat sink 2 a, thereby eliminating any wiring or connectors between the contact 6a and the heat sink 2a. The solenoid 8 is a electrically operated device which keeps movable contact 7 in a normally open position and when actuated, causes the movable contact 7 to be electrically eolid physically connected to contacts 6a to 6b. In one preferred embodiment of the device shown in FIG. Currents flowing in load heat sink 2b are connected to the load slid the load connector or lug zolid.

Connector 10b can be mounted directly on heat sink 2b. While the gating of semiconductors 3a and 3b provide variable control of the currents between the heat sink benzhaw and 2b to the load, shunting solenoid 9 controls a movable shunting contact bar 5 which, when activated, engages stationary contacts 4a and 4b, thereby providing a direct shunt or current bypass between heat sinks 2a and 2b.

Contacts 4a, 4b are stationary and directly mounted to respective heat sinks 2a, 2b. When solenoid 9 is activated such as to connect stationary shunting bar 5 with contacts 4a and 4b, the load current passes from line sstarter sink 2a to load heat sink 2b via contact 4a, movable contact bar 5, and stationary contact 4b.

One way in which the device of FIG. In such embodiment both solenoids 8 and 9 would be in their normally open unenergized position.

When the motor was desired to operate, electric signals would activate solenoid 8 on the incoming line side of assembly 1, causing movable contactor bar 7 to engage stationary contact 6a and 6b, thereby placing incoming heat sink 2a in electrical contact with incoming line lug 10a. During this voltage increasing period, the heat generated in the semiconductor devices 3a and 3b would be conducted away from such devices by heat sinks 2a and 2b.

When the motor reached its desired operating criteria, such as full line voltage, then solenoid 9 would be energized forcing movable contact bar 5 against stationary contacts 4a and 4b. Solic shunting path between adjacent heat sinks created by stationary contact 4a, bar 5, and stationary besnhaw 4b startfr then carry the load current between the adjacent heat sinks 2a and 2b.

Since full load current would no longer be going through the semiconductor devices 3a and 3b, the heat generated in such semiconductor devices would be minimal. Due to the very slight resistive nature of the metallic conducting surfaces of contacts 4a, 4b, 5 the sub-assembly 1 would generate very little of the undesirable heat that is normally associated with solid state control devices.

If at any time during the normal operation it is desired to operate at less than the line voltage, the solenoid 9 can be deenergized and the shunting bar 5 disengaged from respective contacts 4a and 4b, thereby returning the load current path between heat sink 2a and 2b through respective semiconductor devices 3a and 3b.

Incoming lugs 20a, 20c, and 20e can be connected to respective lines in a three phase power system. A three phase load, such as a three phase motor, could be connected between outgoing connectors 20b, 20d, 20f. The assembly shown at 11a operates similar to that shown in FIG.

The current path during conductance is from incoming line connector 20a to stationary contact 16b through movable contactor bar 17a which is operated by line solenoid 18a to engage both contact 16a and 16b.

A stationary contact 16a is mounted on line heat sink 12a. Semiconductors, such as thyristors 13a and 13b, provide gate starfer flow between heat sinks 12a and 12b. Current is conducted from respective thyristors 13a and 13b via load heat sink 12b to lug 20b which can be connected to one phase of the load. When full voltage operation and reduced heating is desired, solenoid 19a is energized causing shorting bar 15a to contact stationary contacts 14a and 14b mounted on the respective heat sinks 12a and 12b.

This assembly 12a uses sgarter separate solenoid for each set of incoming line contacts 16a and 16b. Also a single solenoid actuates a single shorting bar 15a which in turn contacts stationary contacts 14a and 14b. Three devices similar to 11a could be used to create a three phase motor starter.

  EFCO FORMWORK PDF

In such a motor starter each phase would have a separate solenoid operating respective incoming contacts and shunting contacts, so that a total of six solenoids would be used.

As shown in assemblies 11b and 11c, multiple assemblies may be ganged together and have their respective incoming movable contacts 17b and 17b’ actuated from a single electric solenoid 18b. Similarly benehaw shorting contactor bars 15b and 15c can be operated from a single electrically operated solenoid 19b.

While the solenoids 18b and 19b, as shown in FIG. One such embodiment would include a three phase network similar to that shown in FIG. Similarly the movable shunting bar 15a on assembly 11a could be mechanically joined to operate from solenoid 19b. In such an embodiment a three phase solid state motor starter having both incoming line contactors and bypass or shunting contactors on the heat sinks would require only two solenoids, such as 18b and 19b.

In such embodiment there is no need for solenoids 18a and 19a.

Dykman Electrical, Inc. | Benshaw Starters & Controls: Medium and Low Voltage |

Current paths in sub-assembly 11b during operation would include incoming line voltage at lug 20c being conducted benshaww stationary contacts 16d and starfer movable contact 17b to stationary contact 16c which is rigidly attached directly to heat sink 12c. During full voltage operation a current path could exist via semiconductors 13d and 13c which may be respectively gated to their full-on conducting state.

When desired, by actuation of solenoid 19b, a parallel shunting current path would exist through stationary contact 14c which is rigidly affixed to line heat sink 12c and contact 14d which is rigidly affixed to load heat sink 12d, both being joined by movable shunting contact bar 15b. A similar current path exists through sub-assembly 11c in which incoming line voltage at lug 20e is conducted via contact 16f, movable contactor bar 17b’, stationary contact 16e which is affixed to heat sink 12e.

When desired, solenoid 19b is actuated, shunting bar 15c engages stationary contacts 14e and 14f which are respectively mounted on heat sinks 12e and 12f causing a shunting current path between the heat sinks which is parallel to the control gated current flow via semiconductors 13e and 13f.

Current flows from strater load heat sink 12f through the load via aolid 20f. As can be understood, when a plurality of incoming movable contacts are mechanically actuated by a single solenoid, all such movable contacts benxhaw be urged into engagement or disengagement with their respective stationary contacts.

Closure of shunting contacts 14 and 15 can be coordinated with the thyristor gate circuits so as to close when the voltage between adjacent heat sinks is minimum full-on state so as to minimize the voltage rating on the shunting contacts.

Similarly the opening of shunting contacts 14, 15 can be coordinated with the gate circuit to occur only in the full-on state to minimize the voltage and arcing during current interruption at contacts 14, The incoming solenoids such as 18a, 18b can srarter coordinated with the thyristor gating circuit to first phase off the thyristor, reducing the load current to a minimum or trickle value before opening contacts 16, This reduction in wear xtate that can be achieved by such coordination is especially important where contacts 16a,c,e, 14a,b,c,d,e,f are contact surfaces of the heat sink or coated surfaces on benshae aluminum heat sink.

Referring now to FIGS. This embodiment has an incoming power lug 21 and an outgoing lug Incoming heat sink 22 is generally parallel spaced from outgoing heat sink Preferably these heat sinks are made of aluminum. Semiconductor devices 30a and 30b are clamped within the space between heat sinks 22 and Spring clamps 30a, 30b, 30c and 30d are compressed by through bolts to forcibly clamp the semiconductor devices between the heat sinks.

Sate the preferred embodiment semiconductor devices 30a and 30b would be thyristors or silicon controlled rectifiers having well known gating tsarter which control the “on time” to coordinate with the desired load characteristics.

A source of incoming AC voltage, such as a cable, is clamped in incoming power lug 21 which provides electrical power to the incoming stationary contact A dual movable contact or bar 26 can be seen in FIG. Stationary contact 25 is rigidly mounted to incoming heat sink Such rigid mounting comprises an L-shaped bracket extending generally perpendicular to the upper surface of heat sink The contactor surface on contact 25 benxhaw a renewable soliid surface threadably attached perpendicular to the longitudinal direction of the heat sink When the incoming solenoid 27 is activated, moving the armature of the solenoid 27 to the right as viewed in FIG.