Monitoring Unit PAN-A2
The PAN-A2 monitoring unit is used to monitor the REG-D voltage regulator.
The PAN-A2 monitoring unit has its own power supply and is equipped with its own voltage-measurement device. It can therefore be seen as an independent monitoring relay.
The monitoring unit measures the input voltage, independent of the regulator, and compares it to the specified limit values <U, >U, <<U and >>U. If the value exceeds or falls below either the <U or >U limit value, the control commands that are issued in the wrong direction by the regulator are interrupted and this is indicated by LEDs and separate relays. A violation of the <<U and >>U ranges is indicated by a further LED and relay. If the lower voltage limit <U is violated, the lower command from the regulator is interrupted.
If the upper voltage limit >U is violated, the raise command from the regulator is interrupted. The statuses of the "Raise" and "Lower" relays can be inverted using the "Inverse" function. Thus, if the upper voltage limit is exceeded, the lower command of the regulator is interrupted. Similarly, if the lower limit is violated, the raise command is interrupted. This prevents the regulator guiding the voltage to an impermissible range. The monitoring function can be disabled when maintaining or commissioning the REG-D regulator by using a special override input. In this case, if the limit values are violated neither the raise nor the lower command of the regulator can be interrupted.
However, limit value violations continue to be indicated via LEDs and relays. A soft override is automatically generated if the input voltage falls 20% below the setpoint value. In this case the complete monitoring function is disabled. The raise and the lower commands of the regulator are not interrupted, and there is no indication via the LEDs or the special relay. Furthermore, a new firmware version can be loaded using the COM1 interface.