Beijing Sifang CSC-237A Digital Motor Comprehensive Protection and Control Device

1 Device Introduction

This device is suitable for various non-directly grounded neutral systems of 10kV and below, serving as comprehensive protection for phase-to-phase faults, overload, locked rotor, etc., in large and medium-sized asynchronous motors (hundreds of kilowatts and above). It can be installed locally in switchgear cabinets.

10.2 Main Functions

10.2.1 Protection Functions

? Instantaneous overcurrent protection for phase-to-phase faults (optional phase directional element blocking)

? Overcurrent protection for locked rotor conditions

? Overload protection (optional trip or alarm only)

? Long start protection

? Overheating protection (overheat trip, overheat alarm, thermal accumulation memory function)

? Unbalance protection (phase loss/reverse phase, negative sequence overcurrent protection, optional definite time or inverse time)

? Ground fault protection (zero-sequence overcurrent protection, optional trip or alarm only)

? Undervoltage protection

? F-C overcurrent blocking

? Non-electrical protection

10.2.2 Measurement and Control Functions

? 15 channels of digital input for remote signaling collection, device remote signaling status change, accident remote signaling

? Normal circuit breaker remote control opening and closing

? Remote measurement of analog quantities such as Ua, Ub, Uc, Ia, Ic, P, Q, COSф

? Various event SOE, etc.

? 4-20mA function

10.3 Protection Elements

10.3.1 Long Start Protection

The method for the device to measure the motor starting time Tstart: timing begins when the maximum phase current of the motor suddenly changes from zero to 10%Ie, and ends when the starting current peaks and drops to 120%Ie. The duration between these points is called Tstart. (Ie is the motor rated current.) Excessive motor starting time can cause rotor overheating. When the actual measured starting time by the device exceeds the set allowable starting time Tstart, the protection acts to trip. The long start protection can be enabled or disabled by the control word "Motor Start Discrimination".