GEK-45404
8
50 - Cycle Burden at Rated Voltages
RELAY
TYPES VOLTAGE
RATINGS TAP**SETTINGS VOLT-AMPS POWER
FACTOR WATTS
1AV51D 115 A(10) 0.52 0.98 0.52
B(15) 0.67 0.99 0.67
C(25) 1.0 1.0 1.0
D(40) 1.52 1.0 1.52
IAV51D 199 A(16) 0.32 0.85 0.27
B(24) 0.5 0.93 0.46
C(40) 0.83 0.97 0.81
D(64) 1.33 0.99 1.32
IAV51D 345 A(28) 0.39 0.96 0.37
B(42) 0.58 0.98 0.57
C(70) 0.96 0.99 0.95
D(112) 1.35 1.0 1.35
IAV51K 67 A(5.4) 0.38 0.91 0.34
IAV52K B(7.5) 0.52 0.95 0.5
C(12.5) 0.87 0.98 0.85
D(20) 1.42 0.99 1.41
115 No Taps 0.27 0.98 0.27
IAV52C 199 No Taps 0.32 0.85 0.27
345 No Taps 0.39 0.96 0.37
**Minimum pickup volts
OPERATING CHARACTERISTICS
The Ty pe IAV51D relay is a low-pickup voltage relay normally u se d for ground fault protection on
AC rotating machines. It has single-circuit closing contacts that close when the voltage increases to
pickup value, as set on the tap block. The time delay in closing the contacts is determined by t he
setting of the time dial at the top of the shaft. The IAV51D has a capacitor and tapped resistor
connected in series with the operating coil. The capacitor is added to tune the circuit, giving a low
pickup voltage at rated frequency. At rated voltage the operating U magnet is highly saturated,
increasing the impedance of the circuit, thus limiting the current to a safe value. The taps on the
resistor are connected to the tap block to provide a four-to-one range of pickup. As shown in the
typical external connection diagram, Fig. 8, this relay i s connected to the machine neutral potential
transformer through a closed contact on the auxiliary t ripping relay, hence is energized only w h en a
ground occurs. To obtain still-lower pickup than the normal calibration, it is permissible to insert an
inverted potential transformer between the machine neutral transformer and the relay coil circuit.
The IAV51D has a seal-in element. Time curves are shown in Fig. 11.
The IAV51K relay is similar to the IAV51D except that it has an external capacitor. Time curves are
shown in Fig. 11.