The appropriate amplitude of the impulse, direct or. 0 1 c/s
withstand voltage should be determined for every type of equipment
or component during design tests. If impulse tests are
to be used the ratio of the breakdown voltages with full-wave
pulses and with damped oscillatory surges should be established,
and also possible polarity effects and any reduction in b.d.v.
due to the repeated application of surges.