Excitation Loss Module
Excitation Loss available in 12V and 24V for all ranges from UC-P7 of STAMFORD Alternators.
A loss of alternator excitation during parallel operation will result in heavy circulating currents, pole-slipping (loss of synchronization), and torque/current surges and oscillation. The STAMFORD Excitation Loss Module (ELM) monitors the alternator AVR output and signals any sustained interruption to an integral relay to initiate an indication/alarm.
The ELM has been specially designed for use with all Stamford AVRs. It is powered independently from the engine battery at 12 VDC or 24 VDC. It operates by detecting the absence of the characteristic ‘rectifier ripple’ in the exciter field voltage. An optical isolator ensures complete electrical isolation between the exciter field circuit and the engine battery system. Any loss of AVR output is recognised immediately by the monitoring circuit, and if the interruption persists for more than about a second the module output energises an integral relay. The changeover contacts can either provide remote indication of the excitation failure or operate any other relay-fed protective device. The system incorporates a time delay to prevent spurious tripping on transients and an eight-second engine-start lock-out that can be overridden.
Key features include:
- Robust and reliable solid-state electronics
- Independently-powered from the engine battery
- Power supply is completely isolated from exciter field
Engine-start lock-out time delay.
