TRIAC in Light Dimmer cct with snubber blows with motor use

[LeverSpar]

Hello all. Kindly assist with the following problem.
I have built a standard TRIAC controlled light dimmer circuit found in text books. The circuit uses a BT137 TRIAC (8A 600V), a RC snubber circuit and a 5 A fuse.
The circuit functions fine when used to control incandescent light bulbs, however when used to control the speed of Universal motors (commutator type), such as found in a Dremel power tool (220V; 0.4A) the circuit will vary the speed for about a minute or so and then the TRIAC blows and switches permanently on.
The Component values for the snubber circuit have been experimented with, 100 ohm & 0.1uF and 1 Kilo Ohm & 10nF with no success.
Experimenting is becoming a bit expensive, your advice will be much appreciated.

Image of the present circuit diagram.

 

[nashwan]

Re: TRIAC in Light Dimmer cct with snubber blows with motor

hi
the original circuit for dimmer like this u have mistake in drawing just rotate
trigger circuit accros gate.

 

[LeverSpar]

Re: TRIAC in Light Dimmer cct with snubber blows with motor

Thanks. Please correct me if I am wrong, the error with the original circuit that I posted was that the Gate was being triggered with respect to MT2 and not MT1. The TRIAC was blowing due to the Gate voltage exceeding its maximum allowable voltage. Am I correct in saying that rotating the TRIAC so that MT2 and MT1 are swopped around, referring to the incorrect circuit, would fix the problem?