- Direct - on - Line (DOL) or Soft - Start: Some 90KW fire pump control boxes may support direct - on - line starting, where the motor is directly connected to the power supply at full voltage. However, soft - start is more commonly used for larger motors. Soft - start gradually increases the voltage applied to the motor during startup, reducing the inrush current and mechanical stress on the motor and the pump. The soft - start time can typically be adjusted, usually ranging from a few seconds to tens of seconds, depending on the application requirements.
- Star - Delta Starting: Another common starting method is star - delta starting. At startup, the motor windings are connected in a star configuration, which reduces the voltage across each winding and thus the starting current. After a certain time (usually set by a time relay), the windings are switched to a delta configuration for normal operation. The transition time from star to delta can be adjusted according to the motor characteristics.
- Fixed - Speed or Variable - Speed: In a basic fire pump control box, the motor may operate at a fixed speed. However, for more advanced applications, variable - speed control can be implemented using variable frequency drives (VFDs). VFDs allow the motor speed to be adjusted according to the actual demand, such as the required water flow rate in the fire - fighting system. The speed range can typically be adjusted from 0 - 100% of the rated speed, providing more precise control and energy savings.
- Over - current Protection: The control box is equipped with over - current protection devices, such as thermal relays or electronic over - current relays. The over - current setting can be adjusted to a value slightly higher than the rated current, for example, 1.1 - 1.2 times the rated current. When the current exceeds this setting for a certain period, the protection device will trip and cut off the power supply to the motor.
- Over - voltage and Under - voltage Protection: Over - voltage and under - voltage protection settings are also crucial. The over - voltage protection threshold can be set, for example, at 110 - 120% of the rated voltage, and the under - voltage protection threshold at 80 - 90% of the rated voltage. When the voltage goes beyond these limits, the control box will take appropriate actions to protect the motor.
- Phase - loss Protection: Phase - loss protection is essential for three - phase motors. The control box can detect the absence of one or more phases and immediately stop the motor to prevent damage. The sensitivity of the phase - loss detection can be adjusted to ensure reliable operation.
Sichuan Jinhuili Electric Co., Ltd. is specialized in distribution automation, power quality, energy efficiency management of the main products and services; The products include high and low voltage power distribution equipment, uninterruptible UPS power supply, emergency power supply, DC power supply, complete sets of intelligent control equipment, solar photovoltaic power generation, energy storage management, operation and maintenance and other comprehensive automation.
The company is located in Chengdu, Sichuan Province, China, covers an area of more than 10,000 square meters, has a large number of outstanding management personnel, senior engineers and power professional and technical personnel, has been awarded by the government and departments "civilized private enterprise", advanced private enterprise, scientific and technological innovation enterprise, contract-respecting, trustworthy units and other honorary titles.
