3.5.8 Seal-In (Target)
The Seal-In test is performed using DC output current. An AC output current may be applied on
over-current relays to close the trip contacts. Some relays require the user to block the trip
contacts closed to perform this test. The test ramps the DC output at a pre-selected rate see
Test Configuration. The Seal-In test requires the user to press the Stop button, when the Seal-In
contact is closed, since these contacts cannot be monitored by the unit.
3.5.9 Timing
The Timing test is similar to the pulse ramp except is uses a single step. The test steps from a
normal operating condition into the fault condition and waits for the relay to respond. The test
may energize the relay with the normal operating values, then sets the output of the generators to
the fault values, and starts the timer. The timer input monitors the relay constants. The fault
value is a multiple of relay tap settings. This value could be 70%, 80%, 90%, 200%, 300% or
400% depending on the type of relay being tested (voltage or current). The test has three
multiple values and uses each of them until a trip occurs or the last value is used. In some tests,
the user may select IEEE / IEC time curves. Trip times are calculated using preprogrammed
timing formulas per IEEE or IEC standards. However, if IEEE / IEC times curve are not used, or
specific value/trip time tests are to be preformed, the user may manually enter a value(s) and
associated trip time(s) in the appropriate value windows.
3.5.10 Harmonic Restraint
This test uses two current generators. The generators are in phase while the current is being
ramped. The two currents are set to different frequencies. The starting current is determined by
the value entered. With the harmonic current preset (i.e. 1 ampere) the second current channel
(fundamental) will be increased at the preset ramp rate, until the relay trips or the max value is
reached.
3.5.11 Slope
This test uses two current generators. The starting current is determined by the value entered.
The current on one V/I Generator starts at the selected value and is labeled the operate
generator. It starts at (I2 x % Slope x 0.9). The restraint current is set as I2. The operate current
will be increased at the preset ramp rate, until the relay trips or the max value is reached
3.5.12 Through Fault
This test uses two current generators in parallel. The test is executed and the output current is
applied to the relay. The test monitors the relay contact to determine if it is open or closed.
3.5.13 Polarizing
This test uses all three current generators where the output current for each generator is
paralleled at the relay. The test is executed and the output current is applied to the relay. This
test does not monitor any contacts, but does step the generator outputs to the current value
selected. The duration is selected with a maximum time of four cycles to ensure no damage
occurs.
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