Basler Electric BE1-32R - Manual (Page 33)

Figure 3-9. Type D Sensing
Type E Sensing: Two-Phase Current and Three-Phase Voltage
In three-phase, three-wire circuits, relays with type E sensing calculate the power flowing in the tripping
direction by monitoring the three line-to-line voltages and two phases of currents. The relay measures
actual power under balanced or unbalanced conditions. The power equation assumes that conditions are
balanced. Type E sensing configurations are sensitive to phase rotation. The range switch for this sensing
type is calibrated in three-phase watts. Figure 3-10 illustrates the type E sensing configuration.
kW Transducer
Single-phase or three-phase current and voltage signals (determined by the sensing input circuitry type)
are applied to the kW transducer. The signals are applied to a multiplexor that selectively combines the
input conditions and feeds them to a multiplier circuit. The output of the multiplier is true power (watts)
that is then integrated to produce a dc voltage proportional to the monitored power flow. The conditioned,
proportional signal is then applied to the comparator circuits.
Comparator Circuits
A dc signal that represents the monitored power level is applied to the comparator circuits for comparison
with the front panel underpower and overpower settings. When the reference level of the comparators is
surpassed, the appropriate output is energized (if instantaneous timing is selected) or timing is initiated.
Pickup
The overpower pickup point is selected by the front panel Overpower Tap Selector and Range Select
Switch. Table 1-3 lists the overpower pickup range for each sensing input type.
The underpower pickup point is selected by the Underpower Pickup Selector and has an adjustment
range of 10 to 95% of the overpower pickup setting.
Pickup accuracy is ±2% of the front panel setting at unity power factor and ±5% at a power factor above
0.5. The specified accuracy is for current below 10 times the current required to pick up at nominal volts
and unity power factor. The maximum current to maintain specified accuracy can be expressed by the
equation:
10
volts nominal
(setting) watts
×
9171100990 Rev T BE1-32R, BE1-32O/U Functional Description 3-5