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Application Note 2001-01 Rev B

F47 Connections:How to connect a sag generator for SEMI F47 tests

Summary: SEMI F47 requires voltage sag testing of semiconductor manufacturing equipment. You mustconnect a sag generator between your voltage supply -- typically a utility -- and the equipment under test.

Every piece of equipment (and every utility source) has different connection requirements: number ofphases, current requirements, physical location, local practices, etc.

For this reason, most sag generator users construct their own junction boxes.

PSL Application Note 2001-01 shows various practical ways to make these connections.

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SafetyFollow local safety standards and practices when making any electric power connections.The contents of this Application Note show you examples of power connections made byother engineers. These examples may not be appropriate for your application.

Single-phase connectionsThe Sag Generator is connected between the source of power, and the equipment under test.

Photo 1: For low-current single-phase connections, the simplest solution is to break an extension cord.

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Three-phase delta (three-wire) connectionsSags are applied to one phase at a time. The sag generator must be connected in series with each phase,one phase at a time, with the common lead connected to the next phase. For example, a typical test se-quence would be: sag generator in series with L1, referenced to L2; then in series with L2, referenced toL3; then in series with L3, referenced to L1.

Photo 2: A clean, well-made junction box forthree-phase delta. Power from the utility comesinto the box at left, and goes out to the load atright. Cables to the sag generator at at the top.

All ground/PE wires are joined together at ascrew-block partially visible at the bottom.

It is important that the screw terminals be largeenough to accomodate two wires. For example,see the middle screw block at the left: it has boththe reference wire going up to the sag generator,and the L2 wire going to the load.

Photo 3: A similar approach to the one above.The connections to the sag generator have not yetbeen installed.

Note the lack of feed-through protec-tion as the cables enter the box -- thismight not be acceptable under somecircumstances. But temporaryinstallations sometimes have differentrules.

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Three-phase delta (three-wire) connections, continued

Photo 4: A superbly constructedjunction box for 3-phase delta sagtesting. Typically, as testing hasprogressed, some of the power cables areno longer routed through the openingsin the box. Note clear color-coding,grommeting around edges of holes, high-current ground bus.

Photo 5: Another well-madejunction box. Note the clearlabels for input and output.

Also note that the sag generatorconnections, at bottom, include

reference wires for both non-sagged phases (blue and white).

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Three-phase delta (three-wire) connections, continuedSag generators often require temporary connections. Be sure that these connections are safe and reliable.Follow local safety standards and practices.

Photo 6: Sometimes it is necessary to splice an addi-tional cable into the power connections (to carry thepower to the junction box, then back to the EquipmentUnder Test. Be sure the temporary connections are safeand reliable.

These connections will be carefully taped, then individually coveredwith plastic lock-out boxes.

Photo 7: A clever idea: the engineer who installed this junction box recognized that the input and output cables oftenget confused, and has labeled them with white arrows, made from electrician’s tape.

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Three-phase delta (three-wire) connections, continuedSag generators often require temporary connections. Be sure that these connections are safe and reliable.Follow local safety standards and practices.

Photo 8: Another junction box example for three-phase delta.

The power from the utility enters at left, and leavesto the Equipment Under Test at right. The saggenerator connections are at the bottom. (Ignorethe two white wires draped across the top.)

With a box this small, it is sometimes difficult toconnect and re-connect the cables. A larger boxallows larger radii bends on the cables.

Photo 9: A typical junction box being used with anF47 sag generator equipped with a pair of CurrentBoost modules.

Note that the plexiglass wiring covershave been removed from the boostmodules; when there are temporaryconnections, this is sometimes accept-able. Check you local safety standardsand practices.

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Three-phase delta (three-wire) connections, continued

Photo 10,11: Sometimes, for low current applications,simple wiring connections can be made at the fuseddisconnect switch.

This eliminates the need to construct a junction box.

In both photos, note the temporary wiring leavingthrough the door opening of the fuse box, makingit impossible to close the door of the fuse boxduring testing.

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Three-phase wye (four-wire) connectionsSags are applied to one phase at a time, both phase-to-phase and phase-to-neutral. It is typical to do thephase-to-phase and phase-to-neutral tests for a single phase, then move on to the next phase. The saggenerator must be connected in series with each phase, one phase at a time, with the common lead con-nected to the next phase, for phase-to-phase testing, then to the neutral conductor, for phase-to-neutraltesting.

Of course, any of the three-phase-delta junction boxes, shown on the previous pages, could be modified.by adding one more connector (for the neutral conductor).

Photo 12: A clever arrangement that allows you tochange the sag generator connections without turningoff the Equipment Under Test.

Power comes from the utility at the top, and goes to theEquipment Under Test at bottom. The sag generatorwill be connected between the circuit breakers atupper left and lower left.

By turning off the circuit breaker at the right (the“bypass breaker”), the current to the EUT is routedthrough the sag generator. By turning this circuitbreaker on, and turning off the breaker at the upperleft, sag generator connections can be changedwithout disrupting the load.

One caution: turning the bypass breakeron while the sag generator is making asag will damage the sag generator.

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Photo 13: A complicated but safe junction box. Power from the utility comes in through the center conduit, and leavesto the EUT through the left conduit. The cable to the sag generator is at lower right.

Photo 14: It is possible to design a set of“plug-in” cables, one for each phase. A

longer cable (not shown) goes to andfrom the sag generator, and plugs into

the sockets shown here.

This arrangement makes it easy to testout various sag correcting devices and

UPS systems --just plug them in betweenthe source and the load.

Three-phase wye (four-wire) connections, continued

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Three-phase wye (four-wire) connections, continued

Photo 15: Sometimes the simplestsolution is to construct a 3-phaseextension cord with appropriateconnectors. Then break the extensioncord in the middle, and insert the saggenerator as appropriate.

This is similar to the solution shown inPhoto 1.

SafetyFollow local safety standards and practices when making any electric power connections.The contents of this Application Note show you examples of power connections made byother engineers. These examples may not be appropriate for your application.

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