HONEYWELL CC-TAIX01工控備件機器人模塊
熱極限汽車壽命的主要敵人之一是熱量。當指定電機時，買方應告知制造商負載條件和占空比，以及環境和驅動負載的其他相關信息，如啟動扭矩等。然后，制造商應提供庫存電機或制造在這些條件下應具有合理壽命的電機。電機熱極限由定子和轉子的設計決定。電機有三種運行模式：鎖定轉子或失速（當轉子未轉動時）、加速（當轉子達到速度時）和運行（當轉子以接近同步速度轉動時）。在每種情況下，電機都會以非常不同的方式發熱。通常，在電機啟動、鎖定轉子和加速條件下，電機受到轉子限制。也就是說，轉子將在定子之前接近其熱極限。在鎖定轉子條件下，在轉子中感應出線頻率為50或60 Hz的電壓。該電壓導致電流在轉子中流動，也以線頻率流動，產生的熱量（I2R）是有效轉子電阻的函數。在50或60 Hz時，轉子籠的電抗導致電流在轉子棒的外緣流動。因此，轉子的有效電阻在鎖定轉子狀態下達到最大值，轉子加熱也是如此。當電機以額定速度運行時，轉子中感應的電壓處于低頻（約1Hz），因此，轉子的有效電阻顯著降低。在運行過載期間，電機熱極限通常由定子參數決定。某些特殊電機可能全定子或全轉子受限。在加速過程中，電機滑動的動態特性決定了轉子阻抗也是動態的，需要第三個過載熱極限特性。下圖顯示了典型的熱極限曲線。顯示了80%電壓下高慣性負載的電機啟動特性。如果電機啟動更快，則不需要熱極限曲線的明顯特征，運行過載曲線將與鎖定轉子安全失速時間相結合，以產生單個過載曲線。電機制造商應為其銷售的任何電機提供安全失速時間或熱極限曲線。為了對469進行最大程度的保護編程，當電機招標時，有必要詢問這些項目。這些熱限值旨在用作指南，其定義并不總是精確的。當電機運行超過熱極限時，電機絕緣層不會立即熔化。相反，絕緣退化的速度已經達到了這樣的程度：如果電機在這種條件下繼續運行，其壽命將大大縮短。469的主要保護功能是熱模型。它由五個關鍵要素組成：過載曲線和過載拾取水平、電機運行時電機電流的不平衡偏置、電機冷卻時間常數以及基于熱/冷電機信息和測量定子溫度的熱模型偏置。這些元素中的每一個都將在后面的章節中詳細描述。469將定子和轉子加熱集成到一個模型中。電機加熱反映在A1 STATUS？Motor STATUS？？Motor THERMAL CAPITAL USED實際值寄存器中。如果電機長時間停止，則電機將處于環境溫度
THERMAL LIMITS One of the principle enemies of motor life is heat. When a motor is specified, the purchaser communicates to the manufacturer what the loading conditions and duty cycle will be, as well as, environment and other pertinent information about the driven load such as starting torque, etc. The manufacturer then provides a stock motor or builds a motor that should have a reasonable life under those conditions. Motor thermal limits are dictated by the design of both the stator and the rotor. Motors have three modes of operation: locked rotor or stall (when the rotor is not turning), acceleration (when the rotor is coming up to speed), and running (when the rotor turns at near synchronous speed). Heating occurs in the motor during each of these conditions in very distinct ways. Typically, during motor starting, locked rotor and acceleration conditions, the motor is rotor limited. That is to say that the rotor will approach its thermal limit before the stator. Under locked rotor conditions, voltage is induced in the rotor at line frequency, 50 or 60 Hz. This voltage causes a current to flow in the rotor, also at line frequency, and the heat generated (I2R) is a function of the effective rotor resistance. At 50 or 60 Hz, the reactance of the rotor cage causes the current to flow at the outer edges of the rotor bars. The effective resistance of the rotor is therefore at a maximum during a locked rotor condition as is rotor heating. When the motor is running at rated speed, the voltage induced in the rotor is at a low frequency (approximately 1 Hz) and therefore, the effective resistance of the rotor is reduced quite dramatically. During running overloads, the motor thermal limit is typically dictated by stator parameters. Some special motors might be all stator or all rotor limited. During acceleration, the dynamic nature of the motor slip dictates that rotor impedance is also dynamic, and a third overload thermal limit characteristic is necessary. The figure below illustrates typical thermal limit curves. The motor starting characteristic is shown for a high inertia load at 80% voltage. If the motor started quicker, the distinct characteristics of the thermal limit curves would not be required and the running overload curve would be joined with locked rotor safe stall times to produce a single overload curve. The motor manufacturer should provide a safe stall time or thermal limit curves for any motor they sell. To program the 469 for maximum protection, it is necessary to ask for these items when the motor is out for bid. These thermal limits are intended to be used as guidelines and their definition is not always precise. When operation of the motor exceeds the thermal limit, the motor insulation does not immediately melt. Rather, the rate of insulation degradation has reached a point that motor life will be significantly reduced if it is run any longer in that condition. The primary protective function of the 469 is the thermal model. It consists of five key elements: the overload curve and overload pickup level, the unbalance biasing of the motor current while the motor is running, the motor cooling time constants, and the biasing of the thermal model based on Hot/Cold motor information and measured stator temperature. Each of these elements are described in detail in the sections that follow. The 469 integrates stator and rotor heating into one model. Motor heating is reflected in the A1 STATUS ? MOTOR STATUS ?× MOTOR THERMAL CAPACITY USED actual value register. If the motor has been stopped for a long period of time, it will be at ambient temperature and the
