Four-wire three-phase protection wattmeter

Description

Electronic instrument on the front panel (96x96) used to protect generators against overloads and inverse power. The instrument is composed of a power converter with an analogue output connected to the needle indicator with 2 relays. The unit measures and indicates the system's power constantly (measurement in 4 quadrants), sending an alarm signal when the power exceeds the set trip values. The alarm is indicated by activating the output relays. The two LEDS on the front panel can be used to view the status of output relays. The scale is exchangeable.

Applications

The instrument has two independent relays: an overload and an inverse power relay.

Overload protection
The protection has these characteristics:

• Trip point adjustable between 0 and 100% of the scale base power
• Hysteresis adjustable between 1 and 50% of the scale base
• Delay adjustable between 0 and 30 s
• Inverse power protection. With various generators connected in parallel, one can start consuming power and working as a motor, under determined situations ("motorization"). The relay is activated when the circumstances are met.
• The protection system has the following characteristics:Trip point adjustable between 0 and 20% of the scale base power
• Relay interlocking* (latch): when the alarm condition is met, the relay is activated until the instrument's auxiliary power supply is not shut down (even when the alarm conditions disappear)
• Fault security: the relay bypass position is the same as when the alarm is triggered. Therefore, when the auxiliary power supply is shut down, the unit sends an alarm.

* The system can be supplied with no relay interlocking (latch), on demand.

AC power supply

DC power supply

Voltage measurement circuit

Current measurement circuit

Measurement accuracy

Environmental characteristics

Standards

Mechanical characteristics