Description
The digitally controlled KPF221x provide precision (0.2%) high/low frequency protection.

A digital, crystal controlled frequency window discriminator controls operation and delay of the frequency low/high alarm relays. The unit measures the zero point crossing of the voltage true r.m.s. value, and accuracy is independent of any wave form distortion.

The auxiliary voltage is supplied from the unit voltage input. A DC auxiliary voltage input is optionally available. A green LED indicates POWER on. Start of monitoring function is delayed when power is switched on (default 2 secs delay). In this way false tripping during power up is avoided. The precision DIN96 meter reads the frequency directly in Hz, and has low-reflection glass to ease reading at a distance.

The frequency meter and the triple-zone status LEDs at a glance gives the clear safety message:

• HIGH ALARM
• NORMAL
• LOW ALARM
  

The unit has C/O relay outputs for Frequency High Trip (R1) and Frequency Low Trip (R2). A trip LED flashes when the trip level is passed, the relay trips after elapsed delay. The frequency differential set points can be user-adjusted to suit most applications. Trip levels and delays are settable on unit rear.

Red alarm lamps FREQUENCY LOW or FREQUENCY HIGH flash instantly (approx. 1 flash per second) on passing the frequency differential set points. The lamp changes state and the alarm relay operates after the pre-set delay. If a fault condition ends during the delay interval, the timer will automatically reset.

The F-versions have an fast response mA output signal proportional to the Hz range.

The unit meets EN 61010-1 Cat. III, Pollution degree 2 and the relevant environmental and EMC tests specified in EN 61326-2-4 to comply with the requirements of the major Classification Societies.