AUXILARY REALAY MVAA AREVA / ALSTOM

Application The type MVAA is a low burden auxiliary relay which can be used where a scheme demands several contacts for event recording, alarm initiation, contact logic arrangements, etc The relay can be supplied fitted with normal duty contacts and/ or with heavy duty blow-out contacts. Description MVAA relays are voltage operated attracted armature units of compact design with a positive action and a high degree of mechanical stability. Voltage is applied to the relay coils via an internal diode bridge which enables relays to be energised from ac or dc power supplied. All relays comply with IEC 60255. Figures 2 and 3 show typical diagrams of relay types MVAA 11 and MVAA 14 respectively. Contacts Contacts are constructed from silver/ copper alloy, shaped and positioned to ensure very reliable, low resistance operation. Normal duty make, break and changeover contacts and heavy duty magnetic blow-out contacts are available in various combinations. See Tables 1, 2 and 3. Heavy duty magnetic blow-out contacts are recommended for breaking heavy or highly inductive dc loads. When these are fitted, the number of contacts available may be reduced. See Table 3. Breaking capacity curves for these contacts are shown in Figure 4. Operation Indicators Each relay element is supplied with an optional hand reset operation indicator. The indicator consists of a mask which on operation drops to expose a broad red strip positioned diagonally on a rectangular white background.