Electrical

The T & R DVS3 Mk2 offers 3 phase relay testing at a maximum current of 335mA. It features an easy-to-use interface to allow simple testing of complex voltage and loss of mains protection systems. Supplied in Pelicase with DVS-T286, 286V precision step-up box.

The DVS3 is ideal for a wide range of industries including commissioning, laboratory and maintenance. It uses the latest technology creating a stable and accurate output with very low distortion. Individual phase output is adjustable for both voltage and phase angle, with full control of frequency. Step changes of any quantity can be generated with automatic response timing of the relay under test.

In terms of control, the user interface is simple with context sensitive menus. An external keyboard is included for typing values in, or they can be smoothly varied using a digital potentiometer. The LCD is backlit, with menu options having a dedicated button on the panel. This simple layout enables quick access for adjusting voltage, phase and frequency. Both phase to phase and phase to neutral voltage are simultaneously displayed, with frequency and phase information. In addition a graphical vector diagram is shown, along with the state of the two contact inputs.

The DVS3 is suited to testing G59 protection, including loss of mains protection. Along with vector surge and dt/df relays, the DVS3 is also ideal for testing the following:

• Under and over frequency relays
• Under and over voltage relays
• Synchronising relays
• dt / df & ROCOF relays

Transducers

If used with an additional current source, such as the T & R 200ADM or 50A-3PH, the DVS3 mk2 can be used to test protection that requires current injection with a phase-shiftable voltage including:

• Directional relays
• Distance protection
• Phase angle relays
• Power relays
• Power transducers

Variable Frequency Mode

Full control of voltage, frequency and phase is available in this mode. Voltage and phase can either be individually controlled, or for all three phases together. Using the adjust control, you can vary the parameters continuously and you can also use the keypad to enter step changes of any value. New values are applied once the enter key is pressed. When a step change is entered, the timer will automatically reset and start, it stops when contact input is changed. This mode allows for easy step change of phse when testing Vector Surge relays.

Phase Lock Mode

In this mode, the frequency and phase outputs are controlled by an external reference. This reference can either be the mains supply to the DVS3, external voltage or external current. When used with an external current source, this mode will allow the testing or directional and distance problems.

df / dt and ROCOF (Rate of Change of Frequency)

Loss of mains protection often takes the form of a dt / df relay. These are sensitive to the rate of change in frequency over time. With the DVS3 Mk2, you can generate a swept frequency output with accurate rates of change of frequency between the preset frequencies. This rate of change can be varied continuously or stepped to find the relay setting or to time the relay. The output can be set to sweep continuously or generate single sweeps with timing.

Pre-Fault - Fault - Post-Fault Mode

This mode allows for extra flexibility when testing complex events where these events must be timed, or use several sets of values applied in turn to the relay. Three sets of values can be applied in advance and the unit can be set to switch from one state to the next on change of contact, or at a specific time. The timer can also be set to start or stop on any one of the changes of state or a change of contact state. Frequency, voltage and phase can be changed simultaneously when in this mode.