ABB VD4 Series, Addendum Manual

17

—

Periodic checking

CAUTION

Before carrying out any operation, make sure 
that the operating mechanism springs are 
discharged, and that the apparatus is in the 
open position.

General

During normal service, the circuit-breakers are  
maintenance free.

The frequency and sort of inspections basically depend on 
the service conditions. Various factors must be considered: 
frequency of operations, interrupted current values, relative 
power factor and the installation ambient.

The following paragraph gives the checking program table, 
showing the relevant time intervals.

As far as the time interval between these operations is 
concerned, it is advisable to comply with the specifications 
given in the table, at least during the first check. On the 
basis of the results  obtained during the periodic 
inspections, set the optimal time limits for carrying out the 
operations listed in table 2.2 (see page 16).

Table 2.1 

Subject of the 

inspection

Procedure

Positive check

1

Insulation 

resistance

Medium voltage circuits

With a 2500 V megger, measure the insulation resistance between phases 

and exposed conductive part of the circuit.

Auxiliary circuits

With a 500 V megger (installed equipment permitting) measure the 

insulation resistance between the auxiliary circuits and the exposed 

conductive part.

The insulation resistance should be a few MΩ 

and, in any case, constant over time.

The insulation resistance should be at least 50 

MΩ and, in any case, constant over time.

2

Auxiliary 

circuits

Check that the connections to the control circuit are correct; proceed with 

relative supply.

Normal switching and signaling.

3

Manual 

operating 

mechanism

Carry out a few closing and opening operations. N.B. Supply the u/v  

release and the locking magnet on the operating mechanism at the relative 

rated voltage

The operations and relative signals occur 

correctly.

4

Motor 

operator*

Supply the geared motor for spring charging at the relative rated voltage. 

Carry out a few closing and opening operations. N.B. Supply the 

undervoltage release and the locking magnet on the operating mechanism 

at the relative rated voltage. (if provided)

The springs are charged correctly. The signals are 

correct.

The geared motor cuts off when the springs are 

charged.

The geared motor recharges the springs after 

each closing operation.

5

Under voltage 

release*

Supply the undervoltage release at the relative rated voltage and carry out 

the circuit-breaker closing operation. Disconnect the power supply to the 

release.

The circuit-breaker closes correctly. The signals 

are correct.

The circuit-breaker opens. The signal changes 

over.

6

Shunt opening 

release and 

additional 

shunt opening 

release*

Close the circuit-breaker.

Supply the shunt opening release at the relative rated voltage.

The circuit-breaker opens correctly. The signals 

are correct.

7

Shunt closing 

release*

Open the circuit-breaker. Supply the shunt closing release at the relative 

rated voltage.

The circuit-breaker closes correctly. The signals 

are correct.

8

Key lock*

Open the circuit-breaker Turn the key and remove it

Attempt the circuit-breaker closing operation

Insert the key again and turn it 90°

Carry out the closing operation

Neither manual nor electric closing takes place. 

Both electric and manual closing take place 

correctly; in this position the key cannot be 

removed.

9

Locking 

electromagnet

(RL1)*

With the circuit-breaker open, springs charged and locking electromagnet 

not supplied, attempt to close the circuit-breaker both manually and 

electrically.

Closing is not possible.

10

Auxiliary 

contacts in the 

operating 

mechanism

Insert the auxiliary contacts into suitable signaling circuits. Carry out a few 

closing and opening operations.

Signals occur correctly.

11

Racking device 

with lever on 

the unit

With closed circuit-breaker try to operate the lever.

The lever cannot be operated and the racking-out 

are not possible.