Equally at home in a commissioning, maintenance, or laboratory environment, the DVS3 mk2 is a truly flexible system. The DVS3 MK2 has been designed using the latest digital technology to generate a highly stable and accurate output with very low distortion. Each phase output is individually adjustable for voltage and phase angle. In addition, full control of frequency is available. Step changes of any quantity may be generated with automatic timing of the response of the relay under test.
The unit is controlled by a simple user interface with context sensitive menus. Values may be either typed in at the keypad or smoothly varied using a digital potentiometer.
The display on the DVS3 is back-lit and exceptionally clear. Menu options on the left are selected by dedicated buttons on the panel next to the display, allowing immediate access to adjust voltage, phase and frequency. Phase to phase and phase to neutral voltages are both shown on the display, along with frequency and phase information. A graphical vector diagram is shown, as is the state of the two contact inputs.
The DVS3 mk2 is ideally suited to testing G59 protection, including loss of mains protection. Vector surge and df/dt (ROCOF) relays may be simply tested and timed, as can other protection requiring one to three voltages, including:
- Under and over frequency relays
- Under and over voltage relays
- Synchronising relays
- df/dt & ROCOF relays
- Vector surge relays
In conjunction with a current source (such as the 200ADM or 50A-3PH), the DVS3 mk2 can be used to test protection requiring current injection with a phase-shiftable voltage including:
- Directional relays
- Distance protection
- Phase angle relays
- Power relays
- Power transducers
DVS3 mk2 Modes of Operation
Variable Frequency Mode
This mode allows full control of frequency, voltage and phase. The voltage and phase may be controlled individually for each phase or for all three phases together. All parameters are continuously variable using the adjust control, and step changes of any value may be generated by typing the required value on the keypad. The new value is applied to the output when the enter key is pressed. The timer automatically resets and starts when a step change of value is entered, and stops if either contact input changes state. Step changes of phase for testing Vector Surge relays are easily generated in this mode.
|Phase accuracy||±0.3º phase to phase|
Phase Lock Mode
The frequency and phase of the output are controlled by an external reference in phase lock mode. The reference may be the mains supply to the DVS3 MK2, an external voltage, or an external current. This mode allows testing of directional and distance protection in conjunction with an external current source.
|Phase lock range||45-65Hz|
|External voltage ref.||20-250V AC|
|External current ref.||0.2-5A AC|
|Phase accuracy||±0.3º phase to phase|
|±3.0º reference to output|
df/dt and ROCOF (Rate Of Change Of Frequency)
Loss of mains protection often takes the form of a df/dt relay, sensitive to the rate of change of frequency over time. The DVS3 MK2 is able to generate a swept frequency output with accurate rates of change of frequency between preset frequencies. The rate of change may be continuously varied to find the relay setting or stepped to time the relay. The output may be set to either sweep continuously or generate single sweeps with timing.
|Default sweep range||49.75-50.25Hz (50Hz supply)|
|59.75-60.25Hz (60Hz supply)|
|Rate of change range||0.010-2.000Hz/s|
Pre-fault – Fault – Post-fault Mode
PF-F-PF mode allows extra flexibility in testing where complex events must be timed or several sets of values must be applied to a relay in turn. This mode allows three sets of values to be set in advance (pre-fault, fault, and post-fault values). The DVS3 MK2 may be set to switch from one state to the next on a change of contact or after a specific time. In addition, the timer may be set to start or stop on any one of the state changes of a change of contact state. This mode allows frequency, phase and voltage to be changed simultaneously if required.
Output lead set
Lead set case
Spare fuse set
133:266V step up VT box
133:292V step up VT box