When a surge impinges on the line-end coil
of a machine winding, see Figure 1b, it breaks
up into transmitted surges moving away from the
overhang region and a reflected surge travelling
back into the surge source network. As mentioned,
a coil of a machine winding consists of two slot
sections and two end connections, having each of
these regions different electrical characteristics.
The transmitted surges propagate along the overhang
section until they reach the slot entry, where
they encounter a change in surge impedance; this
change causes further reflections and refractions.
Each turn of the coil may be regarded as a single
conductor transmission line coupled to its neighbour
turns, being the end of one turn the start of
the next turn, and the coil can be regarded as a
multiconductor transmission line in that all the
turns run in parallel, see Figure 1. One phase of
the armature winding consists of series connection
of the separate coils of the phase. The complete
model of a machine consists of the models of the
winding phases which can be either delta or star
connected.
Small and large rotating machines behave
differently under high frequency transient voltages.
Small machines, which have many turns or
coils in the same stator slot, have high capacitances
between turns and coils as well as high
mutual inductances, so under transient conditions
they behave like transformers. Larger machines,
which have fewer and longer turns per slot, have
both smaller capacitances between turns and
smaller mutual inductances, and their behaviour
is closer to that of transmission lines (Chowdhuri,
2004).
The number of stator coils in series in formwound
induction and synchronous machines varies
over a considerable range; from a minimum
of three or so in large low-voltage machines to
more than 20 in small high-voltage machines.
A generator, in general, has more coils than a
transformer, but they are connected in parallel.
Generator coils, on the other hand, have relatively
few turns. Hydro generators are different from
turbo generators in that the slots are shorter and
the end regions longer. In addition, they have
more turns per coil than turbo generators. In
general, a generator is connected to its step-up
transformer and the concern is with transients
caused by switching and lightning surges on the
power system that reach the generator through the
step-up transformer, and with disturbances such
as faults and circuit breaker operations occurring
on the generator bus
เมื่อกระชาก impinges บนขดจุดสิ้นสุดบรรทัดของขดลวดเป็นเครื่อง ดูรูป 1b แบ่งค่าเข้าส่งกระชากออกจากoverhang ภูมิภาคและคลื่นสะท้อนการเดินทางกลับเข้าไปในเครือข่ายต้นทางของกระแส ดังกล่าวขดเป็นขดลวดเครื่องประกอบด้วยช่องสองส่วนและการเชื่อมต่อสิ้นสุด 2 มีของลักษณะเหล่านี้ภูมิภาคแตกต่างกันไฟฟ้าพัดนำส่งเผยแพร่ตาม overhangส่วนจนกว่าจะถึงรายการช่อง ที่พวกเขาพบการเปลี่ยนแปลงในกระแสต้านทาน นี้เปลี่ยนแปลงเพิ่มเติมทำสะท้อนและ refractionsเปิดแต่ละของขดลวดอาจถือเป็นซิงเกิลนำสายควบคู่กับของเพื่อนบ้านเปิด การเริ่มต้นของปลายหนึ่งเปิดต่อ และขดลวดสามารถถือว่าเป็นการสาย multiconductor ที่ทั้งหมดเปิดรันพร้อมกัน ดูรูปที่ 1 ขั้นตอนหนึ่งของประกอบด้วยขดลวดกระดองเชื่อมต่อชุดขดลวดแยกของเฟส สมบูรณ์รูปแบบของเครื่องประกอบด้วยรูปแบบของการขดลวดเฟสซึ่งอาจเป็นเดลต้าหรือดาวการเชื่อมต่อขนาดเล็ก และใหญ่เครื่องหมุนทำงานแตกต่างกันภายใต้แรงดันความถี่สูงแบบฉับพลันเครื่องจักรขนาดเล็ก มีเปิดหลาย หรือขดลวดในสเตสล็อตที่เดียว มี capacitances สูงระหว่างเปิดและขดลวดเช่นสูงและ inductances สภาวะชั่วคราวนั้นพวกเขาทำงานเหมือนกับหม้อแปลง เครื่องจักรขนาดใหญ่ซึ่งได้เปิดให้น้อยลง และนานต่อช่อง มีboth smaller capacitances between turns andsmaller mutual inductances, and their behaviouris closer to that of transmission lines (Chowdhuri,2004).The number of stator coils in series in formwoundinduction and synchronous machines variesover a considerable range; from a minimumof three or so in large low-voltage machines tomore than 20 in small high-voltage machines.A generator, in general, has more coils than atransformer, but they are connected in parallel.Generator coils, on the other hand, have relativelyfew turns. Hydro generators are different fromturbo generators in that the slots are shorter andthe end regions longer. In addition, they havemore turns per coil than turbo generators. Ingeneral, a generator is connected to its step-uptransformer and the concern is with transientscaused by switching and lightning surges on thepower system that reach the generator through thestep-up transformer, and with disturbances suchas faults and circuit breaker operations occurringon the generator bus
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When a surge impinges on the line-end coil
of a machine winding, see Figure 1b, it breaks
up into transmitted surges moving away from the
overhang region and a reflected surge travelling
back into the surge source network. As mentioned,
a coil of a machine winding consists of two slot
sections and two end connections, having each of
these regions different electrical characteristics.
The transmitted surges propagate along the overhang
section until they reach the slot entry, where
they encounter a change in surge impedance; this
change causes further reflections and refractions.
Each turn of the coil may be regarded as a single
conductor transmission line coupled to its neighbour
turns, being the end of one turn the start of
the next turn, and the coil can be regarded as a
multiconductor transmission line in that all the
turns run in parallel, see Figure 1. One phase of
the armature winding consists of series connection
of the separate coils of the phase. The complete
model of a machine consists of the models of the
winding phases which can be either delta or star
connected.
Small and large rotating machines behave
differently under high frequency transient voltages.
Small machines, which have many turns or
coils in the same stator slot, have high capacitances
between turns and coils as well as high
mutual inductances, so under transient conditions
they behave like transformers. Larger machines,
which have fewer and longer turns per slot, have
both smaller capacitances between turns and
smaller mutual inductances, and their behaviour
is closer to that of transmission lines (Chowdhuri,
2004).
The number of stator coils in series in formwound
induction and synchronous machines varies
over a considerable range; from a minimum
of three or so in large low-voltage machines to
more than 20 in small high-voltage machines.
A generator, in general, has more coils than a
transformer, but they are connected in parallel.
Generator coils, on the other hand, have relatively
few turns. Hydro generators are different from
turbo generators in that the slots are shorter and
the end regions longer. In addition, they have
more turns per coil than turbo generators. In
general, a generator is connected to its step-up
transformer and the concern is with transients
caused by switching and lightning surges on the
power system that reach the generator through the
step-up transformer, and with disturbances such
as faults and circuit breaker operations occurring
on the generator bus
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